Seismic attenuation of coda waves in the eastern region of Cuba   总被引：1，自引：0，他引：1  

Berta Biescas  Zulima Rivera  Jose Alejandro Zapata 《Tectonophysics》2007,429(1-2):99-109

Cuba's seismic attenuation had never been studied in detail. In this paper we present the results of the research on the seismic attenuation of Cuba's eastern zone based upon the information collected by the seismological Cuban network from 1998 to 2003. 581 earthquakes were selected from the Cuban catalogue to make this study. All of them, recorded by at least three seismic stations, had their epicenters located in the eastern Cuban region (19.3–22 N, 79–73 W), epicentral distances between 15 km and 213 km, their coda duration magnitudes ranging from 2 and 4.1 and their focal depths reaching up to 30 km. The seismic wave attenuation was studied using coda waves. The single scattering method proposed by Sato in 1977 was applied, the attenuation and frequency dependency for different paths and the correlation of the results with the geotectonics of the region are presented in this paper.The mean Q_c value calculated was Q_c = (64 ± 2)f^{0.84 ± 0.01}. The relatively low Q₀ and the high frequency dependency agree with the values of a region characterized by a high tectonic activity. The Q_c values of seven subregions of eastern Cuba were calculated and correlated with the geology and tectonics of the area.  相似文献   

A test of the Tate equation to predict bubble size at an orifice in the presence of frother     

Jose R. Hernandez-Aguilar  Ryan CunninghamJames A. Finch 《International Journal of Mineral Processing》2006

Air bubbles of uniform size (ca. 1 mm diameter) were generated at a submerged orifice (glass capillary) under controlled frequency (down to ca. 0.06 s^− 1) in aqueous solutions of frother (Dowfroth 250). The bubbles were sized with an imaging technique. One objective was to establish whether the Tate equation (static balance between buoyancy and capillary forces) could be used as a standard sizing calibration method. Another aim was to verify whether with decreasing surface tension (due to increasing frother concentration) the anticipated decrease in bubble size agreed with the equation prediction. An effect of frother was detected compatible with the role of surface tension but divided into two concentration regions, seemingly the result of a gradual change in bubble shape and wetting: > 6 ppm the bubble holds a spherical shape and the capillary appeared to be completely wetted while at ≤ 6 ppm a degree of non-wetting and bubble distortion (neck formation just prior to detachment) were apparent, supported by qualitative observations. In addition, at > 6 ppm the Tate value was only approached by decreasing the bubble frequency but not attained. Plausible causes for the failure to reach the predicted size are discussed.  相似文献   

ESTIMATION OF ERRORS IN ABSORBANCE RATIO MEASUREMENTS     

MUHAMMAD SHARAF GARY ARROY RON PERKINS Spectra-Physics Inc.  North First Street  San Jose  CA  U.S.A. 《地理学报(英文版)》1991,(3)

Ratio measurements are commonly used to address a variety of analytical problems in environmental,forensic and pharmaceutical laboratories.In absorbance ratioing techniques,analytical chemists rely onthe spectral features of the analyte(s)of interest.The absorbances at two wavelengths are monitored andthe ratio of these two absorbances is computed.This ratio is then used to confirm the identity of theanalyte(s)of interest,the purity of a product or the overlap of chromatographic peaks.These decisionsoften have far-reaching consequences(e.g.the identification of the source,biogenic or petrogenic,ofhydrocarbons in biological tissues or water).Given the cost and the liabilities associated with suchdecisions,it is unfortunate that these ratios are seldom reported with any statistical confidence.Thepurpose of this study is to delineate the parameters that affect absorbance ratio measurements.Themodels that can be used to estimate the statistical confidence in these measurements are derived andevaluated experimentally.The results show that these models can estimate the relative standard deviationsin absorbance ratios accurately.They can also estimate the effect of signal-to-noise ratio and the choiceof wavelengths on the precision of absorbance ratios.  相似文献   

Variability in habitat use by young-of-the-year winter flounder,<Emphasis Type="Italic">Pseudopleuronectes americanus</Emphasis>, in three northeastern U.S. estuaries     

Ronald?GoldbergEmail author  Beth?Phelan  Jose?Pereira  Stacy?Hagan  Paul?Clark  Allen?Bejda  Anthony?Calabrese  Anne?Studholme  Kenneth?W.?Able 《Estuaries and Coasts》2002,25(2):215-226

We compared distribution and abundance by habitat for age-0, young-of-the-year (YOY) winter flounder,Pseudopleuronectes americanus, in three estuaries (Hammonasset River, Navesink River, and Great Bay-Little Egg Harbor) in the northeastern United States to better define essential fish habitat (EFH). Two replicates of five representative habitats were sampled in most estuaries: eelgrass (Zostera marina), unvegetated areas adjacent to eelgrass, macroalgae, (primarilyUlva lactuca), unvegetated areas adjacent to macroalgae, and tidal marsh creeks. Fish were sampled every two weeks, May through October 1995 and 1996, with a beam-trawl (1-m width, 3-mm mesh net). Abundance of YOY winter flounder was highest in the Navesink River estuary and similar between years, but was significantly lower and differed between years in the Great Bay-Little Egg Harbor and Hammonasset River estuaries. Annual temperature differences appear to influence estuary use by YOY. In the years and estuaries studied, where habitat-related differences in abundance were significant, YOY were found in higher densities in unvegetated areas adjacent to eelgrass. The exception was in the Hammonasset River in 1995 when densities were higher in eelgrass. We conclude that the type of habitat most important to YOY winter flounder varies among estuaries and as a result, care should be taken in defining EFH, based only on limited spatial and temporal sampling.  相似文献   

Three-dimensional V_P and V_S structural models associated with the active subduction and collision tectonics in the Taiwan region     

Kwang-Hee Kim  Jer-Ming Chiu  Jose Pujol  Kou-Cheng Chen  Bor-Shouh Huang  Yih-Hsiung Yeh  Peng Shen 《Geophysical Journal International》2005,162(1):204-220

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Seasonal variability of primary production in a fjord ecosystem of the Chilean Patagonia: Implications for the transfer of carbon within pelagic food webs     

Paulina Montero  Giovanni Daneri  Humberto E. González  Jose Luis Iriarte  Fabián J. Tapia  Lorena Lizárraga  Nicolas Sanchez  Oscar Pizarro 《Continental Shelf Research》2011,31(3-4):202-215

We characterized the seasonal cycle of productivity in Reloncaví Fjord (41°30′S), Chilean Patagonia. Seasonal surveys that included measurements of gross primary production, community respiration, bacterioplankton secondary production, and sedimentation rates along the fjord were combined with continuous records of water-column temperature variability and wind forcing, as well as satellite-derived data on regional patterns of wind stress, sea surface temperatures, and surface chlorophyll concentrations. The hydrography and perhaps fjord productivity respond to the timing and intensity of wind forcing over a larger region. Seasonal changes in the direction and intensity of winds, along with a late-winter improvement in light conditions, may determine the timing of phytoplankton blooms and potentially modulate productivity cycles in the region.Depth-integrated gross primary production estimates were higher (0.4–3.8 g C m^?2 d^?1) in the productive season (October, February, and May), and lower (0.1–0.2 g C m^?2 d^?1) in the non-productive season (August). These seasonal changes were also reflected in community respiration and bacterioplankton production rates, which ranged, respectively, from 0.3 to 4.8 g C m^?2 d^?1 and 0.05 to 0.4 g C m^?2 d^?1 during the productive and non-productive seasons and from 0.05 to 0.6 g C m^?2 d^?1 and 0.05 to 0.2 g C m^?2 d^?1 during the same two periods. We found a strong, significant correlation between gross primary production and community respiration (Spearman, r=0.95; p<0.001; n=12), which suggests a high degree of coupling between the synthesis of organic matter and its usage by the planktonic community. Similarly, strong correlations were found between bacterioplankton secondary production and both gross primary production (Spearman, r=0.7, p<0.05, n=9) and community respiration (Spearman, r=0.8, p<0.05, n=9), indicating that bacterioplankton may be processing an important fraction (8–59%) of the organic matter produced by phytoplankton in Reloncaví Fjord. In winter, bacterial carbon utilization as a percentage of gross primary production was >100%, suggesting the use of allochthonous carbon sources by bacterioplankton when the levels of gross primary production are low. Low primary production rates were associated with a greater contribution of small cells to autotrophic biomass, highlighting the importance of small-sized plankton and bacteria for carbon cycling and fluxes during the less productive winter months. Fecal pellet sedimentation was minimal during this period, also suggesting that most of the locally produced organic carbon is recycled within the microbial loop. During the productive season, on the other hand, the area exhibited a great potential to export organic matter, be it to higher trophic levels or vertically towards the bottom.  相似文献   

An overview of results of processes impacting near-surface atmospheric pollutants (PINESAP) from the mid-Atlantic United States     

Douglas K. Martins  Jose D. Fuentes 《Journal of Atmospheric Chemistry》2015,72(3-4):183-195

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Changes in the storage and sink of carbon dioxide in subsurface atmospheres controlled by climate-driven processes: the case of the Ojo Guareña karst system     

Angel Fernandez-Cortes  Soledad Cuezva  Elena Garcia-Anton  Miriam Alvarez-Gallego  Concepcion Pla  David Benavente  Juan Carlos Cañaveras  Jose Maria Calaforra  David Paterson Mattey  Sergio Sanchez-Moral 《Environmental Earth Sciences》2015,74(12):7715-7730

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Analyzing the commercial activities of a street network by ranking their nodes: a case study in Murcia,Spain     

Taras Agryzkov  Jose L. Oliver  Leandro Tortosa 《International journal of geographical information science》2014,28(3):479-495

Urban researchers and planners are often interested in understanding how economic activities are distributed in urban regions, what forces influence their special pattern and how urban structure and functions are mutually dependent. In this paper, we want to show how an algorithm for ranking the nodes in a network can be used to understand and visualize certain commercial activities of a city. The first part of the method consists of collecting real information about different types of commercial activities at each location in the urban network of the city of Murcia, Spain. Four clearly differentiated commercial activities are studied, such as restaurants and bars, shops, banks and supermarkets or department stores, but obviously we can study other. The information collected is then quantified by means of a data matrix, which is used as the basis for the implementation of a PageRank algorithm which produces a ranking of all the nodes in the network, according to their significance within it. Finally, we visualize the resulting classification using a colour scale that helps us to represent the business network.  相似文献   

Terrain data compression using wavelet-tiled pyramids for online 3D terrain visualization     

Ricardo Olanda  Mariano Pérez  Juan Manuel Orduña  Silvia Rueda 《International journal of geographical information science》2014,28(2):407-425

Last years have witnessed the widespread use of online terrain visualization applications. However, the significant improvements achieved in sensing technologies have allowed an increasing size of the terrain databases. These increasing sizes represent a serious drawback when terrain data must be transmitted and rendered at interactive rates. In this paper, we propose a novel wavelet-tiled pyramid for compressing terrain data that replaces the traditional multiresolution pyramid usually used in wavelet compression schemes. The new wavelet-tiled pyramid modifies the wavelet analysis and synthesis processes, allowing an efficient transmission and reconstruction of terrain data in those applications based on multiresolution tiled pyramids. A comparative performance evaluation with the currently existing techniques shows that the proposed scheme obtains a better compression ratio of the terrain data, reducing the storage space and transmission bandwidth required, and achieving a better visual quality of the virtual terrain reconstructed after data decompression.  相似文献