Hysteretic models that incorporate strength and stiffness deterioration   总被引：2，自引：0，他引：2  

Luis F. Ibarra  Ricardo A. Medina  Helmut Krawinkler 《地震工程与结构动力学》2005,34(12):1489-1511

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Joint estimation of spatial deformation and blurring in environmental data     

A. Goitía  M. D. Ruiz Medina  J. M. Angulo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(1):1-7

Joint estimation of deformation and blurring parameters from spatial observations is considered. The generalized random field approach to the problem introduced in this paper provides a suitable framework for a technical treatment of these effects in relation to singularity properties of the fields. A mixture of Kullback-Leibler divergence loss functions is formulated in a Bayesian context. Simulations are developed to illustrate the performance of the approach proposed.  相似文献   

Strong ground motion estimation in the Sea of Marmara region (Turkey) based on a scenario earthquake   总被引：1，自引：0，他引：1  

Nelson Pulido  Anibal Ojeda  Kuvvet Atakan  Tetsuo Kubo 《Tectonophysics》2004,391(1-4):357

We perform a broadband frequency bedrock strong ground motion simulation in the Marmara Sea region (Turkey), based on several fault rupture scenarios and a source asperity model. The technique combines a deterministic simulation of seismic wave propagation at low frequencies with a semi-stochastic procedure for the high frequencies. To model the high frequencies, we applied a frequency-dependent radiation pattern model, which efficiently removes the effective dependence of the pattern coefficient on the azimuth and take-off angle as the frequency increases. The earthquake scenarios considered consist of the rupture of the closest segments of the North Anatolian Fault System to the city of Istanbul. Our scenario earthquakes involve the rupture of the entire North Anatolian Fault beneath the Sea of Marmara, namely the combined rupture of the Central Marmara Fault and North Boundary Fault segments. We defined three fault rupture scenarios based on the location of the hypocenter, selecting a preferred hypocentral location near a fault bend for each case. We analysed the effect of location of the asperity, within the Central Marmara Fault, on the subsequent ground motion, as well as the influence of anelasticity on the high-frequency attenuation characteristics. The fault and asperity parameters for each scenario were determined from empirical scalings and from results of kinematic and dynamic models of fault rupture. We calculated the resulting time series and spectra for ground motion at Istanbul and evaluated the sensitivity of the predictions to choice of model parameters. The location of the hypocenter is thus shown to be a critical parameter for determining the worst scenario earthquake at Istanbul. We also found that anelasticity has a significant effect on the regional attenuation of peak ground accelerations. Our simulated ground motions result in large values of acceleration response spectra at long periods, which could be critical for building damage at Istanbul during an actual earthquake.  相似文献   

An electoral geography of Western Europe     

Christian Vandermotten  Pablo Medina Lockhart 《GeoJournal》2000,52(2):93-105

The European Parliament elections give the opportunity to map voting behaviour in Western Europe. The main methodological difficulty is related to the classification of the parties. The cleavage theory is not a sufficient basis for an operational typology. The left-right axis remains an important basis for a classification. We have discriminated three groups of parties (the left, including the ecologists; the moderate centre-right and classical right; a growing populist reactionary right and the extreme-right, with a different geographical pattern). Beyond those families, the regionalist parties can also be isolated. The green voting pattern is more specific to the central regions and not linked to that of the traditional left, which is related to the traditions of the workers' movement or more specific to the peripheral regions. In general, the metropolitan regions vote more to the left than the surrounding regions, today more and more often on the basis of an intellectual voting pattern, including some well to-do urban and periurban districts. The centre-right and classical right voting pattern designate two main spaces: a conservative mid-European area, with a strong Christian-democracy in the Catholic countries with a quite recent State building (however recently collapsed in Italy), and rural peripheral spaces, mainly those dominated for a long time by small familial rural enterprises and/or by strong and conservative religious practices. At the European scale, the new populist reactionary right is stronger in the `central' regions than the traditional extreme right, even if the latter is also present in some central deprived urban and old industrial districts.  相似文献   

Recovery of minus ten micron cassiterite by liquid-liquid extraction     

G.Z. Zambrana  R.T. Medina  G.B. Gutierrez  R.R. Vargas 《International Journal of Mineral Processing》1974,1(4):335-345

Fine-size cassiterite can be recovered by a liquid-liquid extraction process using low molecular weight petroleum derivatives and Aerosol-22 as collector. Parameters investigated in this study were pH, collector concentration, and rate of agitation. Depending on agitation rate and collector concentration, rougher concentrates can be up-graded by single cleaning to about 9% tin with a recovery of approximately 78%. After a second cleaning step, recovery decreases to about 50%, while grade increases to about 14% tin. The average tin enrichment ratios (related to the feed) are 6 and 9.4 respectively.  相似文献   

Coastline sand waves on a low-energy beach at “El Puntal” spit, Spain     

G. Medellín  R. Medina  A. Falqus  M. Gonzlez 《Marine Geology》2008,250(3-4):143-156

Coastline sand waves have been observed at “El Puntal” spit, located on the north coast of Spain. The spit has been monitored by an Argus video system since 2003 and the formation and destruction of sand waves has been observed. Coastline data from the video images are analyzed by means of principal components analysis, obtaining a mean sand wave length of 125–150 m and a maximum amplitude of ≈ 15 m. It is also observed that sand waves reach their maximum amplitude at about 15 days. No propagation of these sand waves is noticed during the approximately two-month-long events analyzed. Sand wave formation and evolution are examined in relation with the prevailing local wave conditions during that period. Incident waves at the west end of the spit approach from the east–northeast, with a very high angle with respect to the shoreline. Field observations suggest that sand waves may result from an instability in alongshore sediment transport caused by moderate-energy waves with a high-angle incidence.  相似文献   

Deterministic computer-aided optimum design of rock rubble-mound breakwater cross-sections, by W. de Haan     

Joseph R. Medina 《Coastal Engineering》1992,17(3-4)

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Analysis of an illustrative interaction between structural features and earthworm populations in Brazilian ferralsols     

Michel Brossard  Gustavo Adolfo de Freitas Fregonezi  Maria de Fátima Guimarães  Cristiane de Conti Medina  Amarildo Pasini  Lourival Vilela  Miguel Angel Ayarza 《Comptes Rendus Geoscience》2012,344(1):41-49

Ferralsols are characterized by poorly-defined horizons, weak macrostructure and strong development of a fine granular structure comprising subangular micro-aggregates. In this study, the morphological and physical modifications caused by earthworm activity in a clayey ferralsol were analysed. After describing soil structures, undisturbed samples were taken for evaluating aggregates and determining clod bulk density and particle density. Soil water retention properties were measured and an inventory of soil invertebrate macrofauna was created. The structural and porous transformations were due to aggregates created by earthworm activity. Changes in bulk density can be associated with pore modifications caused by a change in the proportions of aggregate types, and a notable reduction of total porosity was measured, tending to increase soil volume with dense aggregates. Structural modifications affected the topsoil down to 0.5 m and water retention between −1 and −33 kPa, the principal water compartment of these soils.  相似文献   

COSTEP - Comprehensive Suprathermal and Energetic Particle Analyser   总被引：1，自引：0，他引：1  

R. Müller-Mellin  H. Kunow  V. Fleißner  E. Pehlke  E. Rode  N. Röschmann  C. Scharmberg  H. Sierks  P. Rusznyak  S. Mckenna-Lawlor  I. Elendt  J. Sequeiros  D. Meziat  S. Sanchez  J. Medina  L. del Peral  M. Witte  R. Marsden  J. Henrion 《Solar physics》1995,162(1-2):483-504

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Impacts of future climate and land cover changes on landslide susceptibility: regional scale modelling in the Val d’Aran region (Pyrenees,Spain)     

Hürlimann  Marcel  Guo  Zizheng  Puig-Polo  Carol  Medina  Vicente 《Landslides》2022,19(1):99-118

It is widely accepted that future environmental changes will affect rainfall-induced shallow slides in high-mountain areas. In this study, the Val d’Aran region located in the Central Pyrenees was selected to analyze and quantify the impacts of land use and land cover (LULC) and climate changes on regional landslides susceptibility. We analyzed 26 climate models of the EURO-CORDEX database focussing on the future rainfall conditions. The IDRISI TerrSet software suite was used to create the future LULC maps. These two inputs were analyzed individually and in a combined way defining 20 different scenarios. All these scenarios were incorporated in a physically based stability model to compute landslides susceptibility maps. The results showed that both environmental conditions will considerably change in the future. The daily rainfall will increase between 14 and 26% assuming a return period of 100 years. This intensification of precipitation will produce an overall decrease of the stability condition in the study area. Regarding the LULC prediction, the forest area will significantly increase, while in particular grassland, but also shrubs decrease. As a consequence, the overall stability condition improves, because the root strength is higher in forest than in grassland and shrubs. When we analyzed the combined impacts, the results showed that the positive effect of LULC changes is larger than the negative influence of rainfall changes. Hence, when combining the two aspects in the future scenarios, the stability condition in the study area will improve.

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