Robust f‐x projection filtering for simultaneous random and erratic seismic noise attenuation          下载免费PDF全文

Ke Chen  Mauricio D. Sacchi 《Geophysical Prospecting》2017,65(3):650-668

Linear prediction filters are an effective tool for reducing random noise from seismic records. Unfortunately, the ability of prediction filters to enhance seismic records deteriorates when the data are contaminated by erratic noise. Erratic noise in this article designates non‐Gaussian noise that consists of large isolated events with known or unknown distribution. We propose a robust f‐x projection filtering scheme for simultaneous erratic noise and Gaussian random noise attenuation. Instead of adopting the ?₂‐norm, as commonly used in the conventional design of f‐x filters, we utilize the hybrid ‐norm to penalize the energy of the additive noise. The estimation of the prediction error filter and the additive noise sequence are performed in an alternating fashion. First, the additive noise sequence is fixed, and the prediction error filter is estimated via the least‐squares solution of a system of linear equations. Then, the prediction error filter is fixed, and the additive noise sequence is estimated through a cost function containing a hybrid ‐norm that prevents erratic noise to influence the final solution. In other words, we proposed and designed a robust M‐estimate of a special autoregressive moving‐average model in the f‐x domain. Synthetic and field data examples are used to evaluate the performance of the proposed algorithm.  相似文献   

Possible detection of an old bipolar shell associated with η Carinae     

Joaquín Bohigas  Mauricio Tapia  María Teresa Ruiz †  Miguel Roth 《Monthly notices of the Royal Astronomical Society》2000,312(2):295-300

Continuum-subtracted dereddened images in the light of several atomic lines show the presence of an extended bipolar nebula surrounding η Carinae with size ∼100×45 arcsec² (1.3×0.5 pc²). This feature is best delineated in [O  iii ] 5007. The geometrical disposition and mass of the shell suggest that it was formed by mass ejections from η Carinae. The dynamic age of the nebula is ∼13 000/ V ₇ yr, where V ₇ is the mean expansion velocity in 100 km s⁻¹, and its mass is between 5 and 10 M_⊙. The nebula is photoionized and composed of unprocessed material. The major axes of the nebula and of the Homunculus are nearly perpendicular. We also report the discovery of elongated emission knots prominent in [N  ii ] located 64 to 100 arcsec away from η Carinae, which implies that they were ejected either centuries ago or at a more recent date but with extremely large velocities.  相似文献   

Fennoscandia revisited: a spatially improved tree-ring reconstruction of summer temperatures for the last 900 years   总被引：1，自引：0，他引：1  

Hans W. Linderholm  Jesper Björklund  Kristina Seftigen  Björn E. Gunnarson  Mauricio Fuentes 《Climate Dynamics》2015,45(3-4):933-947

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Mesozoic–Cenozoic multistage tectonic evolution of the Pamir: Detrital fission-track constraints from the Tajik Basin     

Lin Li  Yani Najman  Guillaume Dupont-Nivet  Mauricio Parra  Pierrick Roperch  Mustafa Kaya  Niels Meijer  Paul O'Sullivan  Gilby Jepson  Jovid Aminov 《Basin Research》2023,35(2):530-550

Knowledge of the tectonic history of the Pamir contributes to our understanding of both the evolution of collisional orogenic belts as well as factors controlling Central Asian aridification. It is, however, not easy to decipher the Mesozoic–Cenozoic tectonics of the Pamir due to extensive Neogene deformation in an orogen that remains largely understudied. This study reports detrital apatite and zircon fission-track (FT) ages from both the eastern Tajik Basin sedimentary rocks and Pamir modern river sands. These FT data, supported by vitrinite reflectance and zircon and apatite U–Pb double dating, suggest that the majority of the FT ages are unreset and record exhumation stages of the Pamir, which has served as the source terrane of the Tajik Basin since the Cretaceous. Furthermore, we combine the new data with a compilation of published detrital apatite and zircon FT data from both the Tajik Basin sedimentary rocks and Pamir modern river sands, to explore the Mesozoic–Cenozoic tectonic history of Pamir. Deconvolved FT Peak Ages document two major Mesozoic exhumation events associated with the Late Triassic–Early Jurassic Cimmerian orogeny that reflects accretion of the Pamir terranes, as well as the Early–early Late Cretaceous deformation associated with the northward subduction of the Neo-Tethys Ocean beneath Pamir. The compiled data also show significant Late Eocene–Neogene exhumation associated with the ongoing formation of the Pamir, which peaks at ca. 36, 25, 14 and 7 Ma.  相似文献   

Source location of long period seismicity at Volcàn de Colima,México   总被引：1，自引：0，他引：1  

Simona Petrosino  Paola Cusano  Mario La Rocca  Danilo Galluzzo  Justo Orozco-Rojas  Mauricio Bretón  Jesus Ibáñez  Edoardo Del Pezzo 《Bulletin of Volcanology》2011,73(7):887-898

This paper presents an analysis of seismicity associated with the volcanic activity of Volcàn de Colima (México) and recorded in the period November 2005–April 2006 during a field survey by the Istituto Nazionale di Geofisica e Vulcanologia (INGV)–Osservatorio Vesuviano, the Observatorio Vulcanologico de Colima of Colima University and the Instituto Andaluz de Geofisica, University of Granada. Three different types of volcanic earthquakes have been identified on the basis of their spectral properties: Type A (0.3–1 Hz), Type B (1–5 Hz) and Type C (3–4 Hz). Results of polarization analysis applied to Type A events show a predominance of radial motion, indicating that the wavefield comprises compressional waves (P) and shear waves polarized in the vertical plane (SV), while the signal always begins with a negative polarity. Type A, B and C earthquakes have been located using both a flat layered model and a 3D model including topography. Hypocentre distributions indicate that the source of Type A signals is very shallow and confined to a small volume lying about 1 km below the crater. In contrast, the source of Type B and C events is significantly deeper, with most hypocentres located in a volume of about 1 km³ centred at 2.5–3 km depth. A cluster analysis based on the cross-correlation among the waveforms of different events recorded at the same station was applied to Type A earthquakes. Only two clusters, which include only a small percentage of events were found, indicating that earthquake families were uncommon during the period of our survey.  相似文献   

Complex size-dependent habitat associations in potamodromous fish species     

José Maria Santos  Luís Reino  João Oliveira  Paulo Pinheiro  Pedro Raposo Almeida  Rui Cortes  Maria Teresa Ferreira 《Aquatic Sciences - Research Across Boundaries》2011,73(2):233-245

Knowledge of the distribution of species life stages at multiple spatial scales is fundamental to both a proper assessment of species management and conservation programmes and the ability to predict the consequences of human disturbances for river systems. The habitat requirements of three native cyprinid species—the Iberian barbel Barbus bocagei Steindachner, the Iberian straight-mouth nase Pseudochondrostoma polylepis (Steindachner), and the Northern straight-mouth nase Pseudochondrostoma duriense (Coelho)—were examined at 174 undisturbed or minimally disturbed sites in 8 river catchments across western Iberia, by modelling occurrence and counts of species life stages at two spatial scales—large (regional) and instream (local)—using hurdle models. All the life stages of the barbel showed a negative association with upstream high-gradient river reaches, whereas juvenile P. duriense favoured such areas. Stream width and openness were negatively related with the occurrence of juvenile and small adult barbel, but not with large adults. Juvenile nase, on the other hand, were found to be mainly confined to fast-flowing habitats with high instream cover and coarser substrata. Advanced life stages of the barbel were mainly associated with the “pure” regional and shared components, whereas the purely local attributes accounted for much of the model variation among nases, in particular juveniles, and juvenile barbel. The results of this study are useful for setting or refining management goals, and highlight the need to separately consider life stages when performing conservation-related studies of species distribution.  相似文献   

Corrigendum to ‘Pathogenic fungi: An unacknowledged risk at coastal resorts? New insights on microbiological sand quality in Portugal’ [Mar. Pollut. Bull. 62 (2011) 1506–1511]     

Raquel Sabino  Cristina Veríssimo  Maria Ana Cunha  Bela Wergikoski  Filipa C. Ferreira  Raquel Rodrigues  Helena Parada  Leonor Falcão  Laura Rosado  Catarina Pinheiro  Eleonora Paixão  João Brandão 《Marine pollution bulletin》2011,62(12):2880

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Numerical analysis of an embankment built on soft soil reinforced with deep mixing columns: Parametric study     

Paulo J. Venda Oliveira  João L.P. Pinheiro  António A.S. Correia 《Computers and Geotechnics》2011

The behaviour of an embankment built on normally consolidated soft soil reinforced with deep mixing columns is studied using a coupled soil–water formulation. The numerical predictions are analysed in terms of settlements, increments in vertical effective stresses and excess pore pressures. Firstly, the effectiveness of the use of deep mixing columns is studied. Afterwards, a parametric analysis is performed to study the influence on the soil-columns system of the replacement ratio (columns’ spacing), the deformability of the embankment and columns, and the coefficient of vertical permeability of the columns.  相似文献   

Impact of crab bioturbation on benthic flux and nitrogen dynamics of Southwest Atlantic intertidal marshes and mudflats   总被引：1，自引：0，他引：1  

Eugenia Fanjul  María C. Bazterrica  Mauricio Escapa  María A. Grela  Oscar Iribarne   《Estuarine, Coastal and Shelf Science》2011,92(4):387

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Free Eu(III) Determination by Donnan Membrane Technique with Electrochemical Detection: Implementation and Evaluation     

Janot  Noémie  Groenenberg  Jan E.  Otero-Fariña  Alba  Pinheiro  José Paulo 《Aquatic Geochemistry》2021,27(2):127-140

Aquatic Geochemistry - The aim of this study was to develop an analytical method to determine free concentrations of Europium (Eu(III)) in natural waters. Europium(III) in solution was detected...  相似文献