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71.
72.
Although there is a consensus on the necessity of monitoring solid wastes pollution on beaches, the methods applied vary widely. Therefore, creating, testing and recommending a method that not only allows comparisons of places and periods, but also the detection of source signals, will be important to reach the objectives of the source-prevention principle. This will also allow the optimisation of time, resources, and processing of samples and data. A classification of the items found into specific categories was made according to their most probable source/use (fisheries, food packaging, hazardous, sewage/personal hygiene, beach user, general home). This study tested different widths of sampling transects to be used in the detection of plastics contamination on beaches, until all the categories were significantly represented. Each transect had its total width (50m) sub-divided into eight intervals of 0-2.5m; 2.5-5m; 5-10m; 10-15m; 15-20m; 20-30m; 30-40m; and 40-50m. The accumulated number of categories in the 50m (up to 2.5m; up to 5m and so on) was used to determine the minimal width necessary to qualitatively characterize the area regarding plastics contamination. The diversity of the categories was directly related to the area of the sampling transect. These results indicate that a significant increase in the number of categories in the first intervals tend to stabilize from 15-20m onwards. 相似文献
73.
Odim Mendes Jr. Aracy Mendes da Costa Fernando Celso Perin Bertoni 《Journal of Atmospheric and Solar》2006,68(18):2127-2137
For at least 30 years now it has been well known that the Dst index can be modelled using the solar wind as input. Since then, many attempts have been made to improve the predictability of Dst using different approaches. These attempts are useful, for instance, to understand which features of the solar wind–magnetosphere interactions are most important in producing magnetospheric activity and how the Dst index would improve the space weather forecast. The Dst index is by far the most reliable and simple indication that a magnetic storm is in progress. In this work, the effect of using more than four magnetic stations and shorter time intervals than the hourly averages used in Sugiura's procedures is evaluated. The discussion is based on the results presented by Burton in 1975 and Feldstein in 1984 considering 4 or 12 magnetic stations and time averages of 2.5 min for a magnetic disturbed period that occurred from February 7–28, 1967, including two geomagnetic storms. The analysis has shown that the global representation of a magnetic storm by the standard Dst (Sugiura) is well preserved either using 4, 6, 12 magnetic stations or using 1 h, 2.5 min 1 min averages. A brief review of the current understanding of Dst has been included to support the discussions. The analysis performed has shown that a more refined Dst index (time and number of stations>4) would be useful to investigate the intrinsic processes and the different current systems involved in the ring current development during magnetic storms; the standard Dst, as it is conceived, is quite adequate to monitor geomagnetic storms and identify their overall features; concerning the magnetic stations normally considered, the inclusion of higher magnetic latitude stations (>35) may underestimate the observed Dst. 相似文献
74.
75.
Jaqueline C. Rodrigues Tania Maria Haas Costa Márcia R. Gallas Celso C. Moro 《Physics and Chemistry of Minerals》2009,36(8):439-446
We investigate the structural evolution of synthetic layered double hydroxides (LDH) samples, processed at room temperature
and high-pressure (up to 7.7 GPa) in a toroidal chamber with two pressure-transmitting media, lead and graphite, using X-ray
diffraction, thermogravimetry and N2-adsorption isotherms techniques. The X-ray patterns of compacted samples show a decrease in the peak intensities. For both
pressure-transmitting media, our samples revealed a reduction of the basal d-spacing for the (003) plane when processed at
7.7 GPa. The expected high-pressure-induced amorphization was not observed. Surprisingly, we find high-pressure processing
to have a strong influence on the memory effect of the LDH, due essentially to the reduction of the surface area and pore
closing. Even when immersed in water, our samples did not recover the LDH structure, when either calcined at 450°C and compacted
at 7.7 GPa, or calcined at 700°C and immediately compacted at 2.5 and 7.7 GPa. 相似文献
76.
Salles Lucas A. Vani Bruno C. Moraes Alison Costa Emanoel de Paula Eurico R. 《Surveys in Geophysics》2021,42(4):999-1025
Surveys in Geophysics - Over the last 15 years, the satellite constellation of the global positioning system (GPS) has been modernized for more precise applications, with the introduction... 相似文献
77.
da Silva Richarde Marques Santos Celso Augusto Guimarães Silva Jorge Flávio Casé Braga da Costa Silva Alexandro Medeiros Brasil Neto Reginaldo Moura 《Natural Hazards》2020,104(2):1953-1954
Natural Hazards - The article “Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment, Paraíba, Brazil”, written by da... 相似文献
78.
Rafael Moniz Caixeta Diniz Tamantini Ribeiro João Felipe Coimbra Leite Costa Péricles Lopes Machado 《Natural Resources Research》2017,26(2):213-221
Multiple Random Walk Simulation consists of a methodology adapted to run fast simulations if close-spaced data are abundant (e.g., short-term mining models). Combining kriging with the simulation of random walks attempts to approximate traditional simulation algorithm results but at a computationally faster way when there is a large amount of conditioning samples. This paper presents this new algorithm illustrating the situations where the method can be used properly. A synthetic study case is presented in order to illustrate the Multiple Random Walk Simulation and to analyze the speed and goodness of its results against the ones from using Turning Bands Simulation and Sequential Gaussian Simulation. 相似文献
79.
V. M. Costa J. F. Gameiro M. T. V. T. Lago 《Monthly notices of the Royal Astronomical Society》1999,307(3):L23-L26
We combine calibrated International Ultraviolet Explorer ( IUE ) archive data and new low-resolution optical data for the T Tauri star LkH α 264 covering the region from 1200 to 7000 Å. The UV continuum is well fitted by the combination of a blackbody at 4300 K plus hydrogenic free–free and free–bound emission from a dense plasma at 3.5×104 K plus the emission by a second blackbody. This last component is at T ≈8700 K and covers about 4 per cent of the stellar surface. We interpret this last component to be the result of emission from one or various hotspots. The interesting result is that this combined emission also fits the observed optical continuum well. We conclude that this star is an analogue of the Sun, however displaying a much higher level of activity. 相似文献
80.