Experimental characterization of the out-of-plane performance of regular stone masonry walls,including test setups and axial load influence     

Tiago Miguel Ferreira  Alexandre A. Costa  António Arêde  Ana Gomes  Aníbal Costa 《Bulletin of Earthquake Engineering》2015,13(9):2667-2692

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Source Separate Collection of Recyclables Reduces Chromium and Nickel Content in Municipal Solid Waste Compost          下载免费PDF全文

Rafael López  Pilar Burgos  Fernando Madrid  Ignacio Camuña 《洁净——土壤、空气、水》2015,43(3):427-433

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Hydrological implications of land use and land cover change: Spatial analytical approach at regional scale in the closed basin of the Cuitzeo Lake,Michoacan, Mexico     

M.E. Mendoza  G. Bocco  E. López‐Granados  M. Bravo Espinoza 《Singapore journal of tropical geography》2010,31(2):197-214

A spatially distributed water balance model was used to assess the influence of regional land use and land cover change in a poorly gauged basin for the years 1975 and 2000. To carry out this study in the Cuitzeo Lake basin in Michoacan, Mexico, remote sensing and geographic information system tools were integrated in the water balance model. In addition, a transition matrix analysis was used to determine the dynamic change of categories of related hydrologic processes. The analysis of the water balance components, based on landforms and transition matrix, indicated a tendency of improvement in the regional hydrologic conditions in the basin. As a consequence of urban land use growth, however, plains and footslopes of the basin showed an increase of runoff values. In addition, in both years, the topographic lower sections of the basin exhibited a high demand for water from the increased urban land use, along with degradation of Cuitzeo Lake, particularly by pollution and reduction of water supply. The approach used here is suitable for understanding the change in quantity and spatial distribution of water available in poorly gauged basins.  相似文献   

Ongoing research on seismic safety assessment     

Raimundo Delgado  Aníbal Costa  António Arêde  Nelson Vila Pouca  João Guedes  Xavier Romão  Pedro Delgado  Patrício Rocha 《Bulletin of Earthquake Engineering》2010,8(1):181-199

Research on seismic safety assessment has been the centre of great interest among the scientific community in recent years. Although the devastating impact of earthquakes on current society should be incentive enough to increase research, the development of more realistic mechanical behaviour models and the continuous enhancement of computation capabilities are paramount factors contributing a great deal to the increase of such interest. In this context, three research areas can be identified as currently leading to important developments: code related research, especially in Europe where new design codes are in the implementation process; risk analysis, namely concerning the definition of methodologies for safety assessment that involve the evaluation of the failure probability and could be included in future generations of codes; and experimental characterization of constitutive laws which provides support for the development and calibration of accurate and realistic numerical models for seismic analysis and for the adequate characterization of limit state capacities. The paper will present some of the current scientific research trends on these three seismic safety assessment related topics. Studies addressing the seismic safety assessment of structures, either probabilistically or based on code provisions, and that consider realistic nonlinear mechanical behaviour models will be focussed. Reference will also be made to experimental research on the seismic behaviour of structural elements, emphasizing its crucial role to support the development of numerical models simulating the effects of different seismic strengthening techniques. Finally, given the development of studies leading to new trends and perspectives for performance based earthquake engineering, a possible scenario for seismic design in the future is presented, emphasizing the key issues for its implementation.  相似文献   

K-feldspar IRSL dating of a Pleistocene river terrace staircase sequence of the Lower Tejo River (Portugal,western Iberia)     

António A. Martins  Pedro P. Cunha  Jan-Pieter Buylaert  Sébastien Huot  Andrew S. Murray  Pedro Dinis  Martin Stokes 《Quaternary Geochronology》2010,5(2-3):176-180

We present the results of K-feldspar IRSL dating of the four lower terraces (T3–T6) of the Portuguese Tejo River, in the Arripiado-Chamusca area. Terrace correlation was based upon: a) analysis of aerial photographs, geomorphological mapping and field topographic survey; b) sedimentology of the deposits; and c) luminescence dating. Sediment sampled for luminescence dating gave unusually high dose rates, of between 3.4 and 6.2 Gy/ka and, as a result, quartz OSL was often found to be in saturation. We therefore used the IRSL signal from K-feldspar as the principal luminescence technique. The K-feldspar age results support sometimes complex geomorphic correlations, as fluvial terraces have been vertically displaced by faults (known from previous studies). Integration of these new ages with those obtained previously in the more upstream reaches of the Tejo River in Portugal indicates that the corrected K-feldspar IRSL ages are stratigraphically and geomorphologically consistent over a distance of 120 km along the Tejo valley. However, we are sceptical of the accuracy of the K-feldspar ages of samples from the T3 and T4 terraces (with uncorrected D_e values >500 Gy). In these cases the Dose Rate Correction (DRC) model puts the natural signals close to luminescence saturation, giving a minimum corrected D_e of about 1000 Gy, and thus minimum terrace ages; this may even be true for those doses >200 Gy. Luminescence dating results suggest that: T3 is older than 300 ka, probably ca. 420–360 ka (～Marine Isotope Stage [MIS]11); T4 is ca. 340–150 ka (～MIS9-6); T5 is 136–75 ka (～MIS5); T6 is 60–30 ka (MIS3); an aeolian sand unit that blankets T6 and some of the older terraces is 30–≥12 ka. Collectively, the luminescence ages seem to indicate that regional river downcutting events may be coincident with periods of low sea level (associated, respectively, with the MIS10, MIS6, MIS4 and MIS2).  相似文献   

Particulate matter geochemistry of a highly industrialized region in the Caribbean:Basis for future toxicological studies     

Luis F.O.Silva  Ismael L.Schneider  Paulo Artaxo  Yuleisy Núñez-Blanco  Diana Pinto  Érico M.M.Flores  Leandro Gómez-Plata  Omar Ramírez  Guilherme L.Dotto 《地学前缘(英文版)》2022,(1):376-387

Air pollution has become an important issue,especially in Caribbean urban areas,and,particulate matter(PM)emitted by different natural and anthropogenic sources causes environmental and health issues.In this work,we studied the concentrations of PM₁₀ and PM_2.5 sources in an industrial and port urban area in the Caribbean region of Colombia.PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000 i-D sampler.Elemental geochemical characterization was performed by X-ray fluorescence(XRF)analysis.Further,ionic species and black carbon(BC)were quantified by ion chromatography and reflectance spectroscopy,respectively.Using the Positive Matrix Factorization(PMF)receptor model,the contributions of PM sources were quantified.The average concentration of PM₁₀ was 46.6±16.2μg/m³,with high concentrations of Cl and Ca.For PM_2.5,the average concentration was 12.0±3.2μg/m³,and the most abundant components were BC,S,and Cl.The receptor model identified five sources for PM₁₀ and PM_2.5.For both fractions,the contributions of marine sea spray,re-suspended soil,and vehicular traffic were observed.In addition,PM_2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions,and secondary aerosol sources with building construction emissions.Further,PM₁₀ was found to also include building construction emissions with re-suspended soil,and metallurgical industry emissions.These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region.  相似文献   

Hydrogeological characterization of carbonated Jurassic aquifers in the Gijón-Villaviciosa basin (Asturias,N Spain) by means of geochemical and isotopic techniques     

Beatriz González-Fernández  Mónica Meléndez-Asensio  Eduardo Menéndez-Casares 《Environmental Earth Sciences》2009,59(4):913-928

Chemical and isotopic analyses of groundwater from the carbonated Jurassic aquifers in the Gijón-Villaviciosa basin (Asturias, northern Spain) were carried out. Nine springs were sampled to determine major cations and anions, as well as the stable isotopes of the water molecule (δ²H and δ¹⁸O) and sulphate (δ³⁴S) values. Also, δ³⁴S values from gypsum coming both from Triassic rocks and bottom of Jurassic sequence were also determined. The results obtained were used to classify the waters with a genetic criteria in three groups: (1) waters with a high gypsum influence, with sulphate coming from Jurassic gypsum, (2) waters without gypsum influence, where sulphate source could be atmospheric deposition from industrial processes and marine aerosol, and (3) waters with some gypsum influence, in which sulphate origin could be a combination of different sources. In relation to recharge, δ²H and δ¹⁸O values were close to those of Global Meteoric Water Line and fit a local line that suggests a meteoric origin. The estimated elevations for spring recharge are in agreement with those obtained from hydrogeological maps.  相似文献   

Application of Multiple Point Geostatistics to Non-stationary Images   总被引：5，自引：2，他引：3  

Luis Manuel de Vries  Jesus Carrera  Oriol Falivene  Oscar Gratacós  Luit Jan Slooten 《Mathematical Geosciences》2009,41(1):29-42

Simulation of flow and solute transport through aquifers or oil reservoirs requires a precise representation of subsurface heterogeneity that can be achieved by stochastic simulation approaches. Traditional geostatistical methods based on variograms, such as truncated Gaussian simulation or sequential indicator simulation, may fail to generate the complex, curvilinear, continuous and interconnected facies distributions that are often encountered in real geological media, due to their reliance on two-point statistics. Multiple Point Geostatistics (MPG) overcomes this constraint by using more complex point configurations whose statistics are retrieved from training images. Obtaining representative statistics requires stationary training images, but geological understanding often suggests a priori facies variability patterns. This research aims at extending MPG to non-stationary facies distributions. The proposed method subdivides the training images into different areas. The statistics for each area are stored in separate frequency search trees. Several training images are used to ensure that the obtained statistics are representative. The facies probability distribution for each cell during simulation is calculated by weighting the probabilities from the frequency trees. The method is tested on two different object-based training image sets. Results show that non-stationary training images can be used to generate suitable non-stationary facies distributions.  相似文献   

Stable isotope characterisation of co-existing carbonates from the Holocene Gallocanta lake (NE Spain): palaeolimnological implications     

A. Luzón  M. J. Mayayo  A. Pérez 《International Journal of Earth Sciences》2009,98(5):1129-1150

The sedimentary succession of Gallocanta lake, a closed saline lake located in the Iberian Range (NE Spain), documents two successive lacustrine stages: (1) brackish lake stage and (2) shallow saline lake stage. The saline stage corresponds to the present-day situation in which the lake water properties are mainly controlled by a strongly negative annual water balance. The carbonates of the brackish lake stage have relatively constant δ¹⁸O values, however, they are rather high (δ¹⁸O_Do = 2.4‰ and δ¹⁸O_Cc = 4.5‰ mean values) suggesting a hydrologically closed lake with a long residence time of the waters. δ¹⁸O values of carbonates from the saline stage vary greatly, and are lighter than in the previous stage (δ¹⁸O_Do = 0.5‰, δ¹⁸O_Cc = −0.7‰, δ¹⁸O_Mgs = −2.3‰ mean values). These carbonates also precipitated in a hydrologically closed lake, but in equilibrium with a lake water of more variable isotopic composition. The δ¹³C values for carbonates of both stages reflect a mixing of different pools of carbon, but during saline stage δ¹³C values have been more controlled by the equilibrium of the lake waters with atmospheric CO₂. During the current stage, calcite and dolomite precipitate in Gallocanta lake mainly during spring and summer, although dolomite precipitation is more favoured towards the summer. Magnesite precipitates at the beginning of autumn, when the first rainfall re-dissolves the saline surface crust, producing saline waters with a high Mg²⁺ content. The isotopic composition of lake waters sampled in 2005 are far higher than those calculated from the carbonates. It is considered that this could be due to two factors: either because there have not been many extremely dry years (like the year 2005) during the development of the lake, or because the physical and chemical characteristics of the lake waters in such conditions are not appropriate for the development of these minerals.  相似文献   

A rootless suture and the loss of the roots of a mountain chain: The Variscan belt of NW Iberia     

José R. Martínez Catalán  Ricardo Arenas  Jacobo Abati  Sonia Sánchez Martínez  Florentino Díaz García  Javier Fernández Suárez  Pablo González Cuadra  Pedro Castiñeiras  Juan Gómez Barreiro  Alejandro Díez Montes  Emilio González Clavijo  Francisco J. Rubio Pascual  Pilar Andonaegui  Teresa E. Jeffries  James E. Alcock  Rubén Díez Fernández  Alicia López Carmona 《Comptes Rendus Geoscience》2009,341(2-3):114-126

Ophiolites of different Paleozoic ages occur in North-West (NW) Iberia in a rootless suture representing the remnants of the Rheic Ocean. Associated allochthonous terranes in the hanging- and foot-walls of the suture derive from the former margins, whereas the relative autochthon corresponds to the Paleozoic passive margin of northern Gondwana. The Paleozoic tectonic evolution of this part of the circum-Atlantic region is deduced from the stratigraphical, petrological, structural and metamorphic evolution of the different units and their ages. The tectonic reconstruction covers from Cambro-Ordovician continental rifting and the opening of the Rheic Ocean to its Middle to Upper Devonian closure. Then, the Variscan Laurussia–Gondwana convergence and collision is briefly described, from its onset to the late stages of collapse associated with the demise of the orogenic roots.  相似文献