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31.
In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters. 相似文献
32.
The present paper deals with the pulsation period variability of the high-amplitude δ Scuti star GP Andromedae using a data
set covering a time base of 26.9 years. The possibility of a periodic component (reflecting the light-time effect induced
by a hypothetic binarity) in the O-C curve is inferred. The presence of this periodicity in the period variation of GP And leads to a diminution of the discrepancy
between predicted and observed relative period change rates. The hypothesis of the existence of an unseen companion is discussed.
The statistical analysis of the final O-C residuals distribution, indicates their normal or close to normal character.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
33.
Cristian Mattar Andrés Santamaría-Artigas Flavio Ponzoni Cibele T. Pinto Carolina Barrientos Glynn Hulley 《International Journal of Digital Earth》2019,12(1):43-61
This work presents the preliminary results of the first field calibration campaign performed in the Atacama Desert, Chile, between the 18 and 22 August 2014, called the Atacama Field Campaign (ATAFIC 2014). In situ measurements were performed in order to spectrally characterize the surface reflectance spectra between 0.3 and 2.5?µm, radiometric temperature (8.0–14.0?µm) and atmospheric measurements. A soil sample was collected and analyzed using Fourier Transform Infrared Spectroscopy and X-Ray Diffraction techniques to characterize the surface reflectance spectra and mineralogical composition, respectively. ASTER land surface emissivity in addition to GOES, MODIS and Landsat-8 land surface temperature (LST) were also used. Results showed that the spectral features of the Atacama soil and the characteristics of this geographical zone, which is featured as the most hyper-arid and cloudless place in the world, make this area a potential target for surface reflectance characterization. Day and night LST comparison between field and remote sensing data are lower than 2?K and the Root Mean Square Error for land surface emissivity is close to 2%. This work opens the possibilities to consider the Atacama Desert as a reference target for calibration and validation activities for earth observation missions’ purposes. 相似文献
34.
Natural Hazards - Empirical relationships between MSK macroseismic intensity and several engineering ground motion parameters are developed using the macroseismic and instrumental data available... 相似文献
35.
Cristian Flueraru Gheorghe Stancalie Vasile Craciunescu Elena Savin 《Transactions in GIS》2007,11(6):927-941
The MODIS snowcover product is one of many geophysical products derived from MODIS data. A cross‐validation of the MODIS snowcover daily products with data obtained from the meteorological network stations was conducted for the entire territory of Romania. The validation time interval covered the period between 29 October, 2004 and 1 May, 2005. The overall accuracy for the whole set of cloud‐free useful data proved to be 95%. The validation time interval included the three common snow situations: (1) late autumn months where 37.1% of the initial set of the data was used, and the overall accuracy was 98.6%; (2) the “winter” months where the clouds reduced the set of useful data – 31.75%– and the overall accuracy was 93.7%; and (3) the months of February and March which returned the highest accuracy (> 95%). Additionally, a cross‐validation using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) high‐resolution imagery was carried out. Furthermore, the MODIS, meteorological data and ASTER data were integrated into a Geographic Information System (GIS) environment to perform flexible and comprehensive cross‐checking followed by a thematic analysis based on additional sets of data such as digital elevation models (DEMs) and land‐cover datasets. 相似文献
36.
Photoelectric observations of the asteroid 433 Eros were carried out with the 50-cm reflector of the Astronomical Observatory of the University of Cluj-Napoca on January 21 and February 4 and 5, 1975. 相似文献
37.
We present a numerical scheme for reactive contaminant transport with nonequilibrium sorption in porous media. The mass conservative scheme is based on Euler implicit, mixed finite elements, and Newton method. We consider the case of a Freundlich-type sorption. In this case, the sorption isotherm is not Lipschitz but just Hölder continuous. To deal with this, we perform a regularization step. The convergence of the scheme is analyzed. An explicit order of convergence depending only on the regularization parameter, the time step, and the mesh size is derived. We give also a sufficient condition for the quadratic convergence of the Newton method. Finally, relevant numerical results are presented. 相似文献
38.
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
39.
Jorge Yáñez Marjory Guajardo Cristian Miranda César Soto Héctor D. Mansilla A. Russell Flegal 《Marine pollution bulletin》2013
Anomalously high levels of mercury in sediment in the Lenga estuary, Chile are comparable to the most contaminated sites previously reported elsewhere. Total mercury (Hgtotal) concentrations range from 0.5 to 129 mg kg−1 and organic mercury (Hgorg) from 11 to 53 μg kg−1. The highest levels are in areas near the previous wastewater outfall of a chlo-alkali plant. The results show that the proportion of Hgorg/Hgtotal in the sediment varies by more than two orders of magnitude (0.02–5.7%) according to the concentration of Hgtotal. No correlation between the concentration of Hgorg and Hgtotal was found. The lack of correlation does contrast with the findings of other authors in culture media. Our results indicate that even at very high concentrations of Hgtotal and organic matter do not influence organic mercury formation in estuary sediments. The disparity in Hgtotal and Hgorg concentrations also attests to environmental differences in the formation. 相似文献
40.