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1.
J. Enrique Luco Francisco C. P. de Barros 《Soil Dynamics and Earthquake Engineering》2004,24(12):1013-1035
Blind predictions for the response of the 1/4-scale reinforced concrete Hualien (Taiwan) containment model during forced vibration tests are compared with the observed data. The predictions obtained by the CLASSI approach reflect the experimental conditions prior to and after backfill of the soil surrounding the embedded foundation. The experimental data show a strong and unexpected coupling between the response in the NS and EW directions which is not present in the results for the axisymmetric theoretical models. Also, significant differences can be seen between the experimental responses in the two orthogonal horizontal directions which minimize cross-axis coupling. Although these differences are not accounted for in the theoretical models, the discrepancies between predictions and observations are within the uncertainty of the structural and geotechnical data. The obtained differences between predictions and observations give an excellent measure of the prediction error that can be expected in this type of analysis from uncertainty in the data. A detailed assessment of the initial structural and geotechnical data based on extensive comparisons with the results of previous identification studies is also presented. Finally, comparisons between the observed response and calculations based on revised models for the structure and the soil show that current methods of analysis can account accurately for the observed response. 相似文献
2.
Enrique Muñoz José Luis Arumí Thorsten Wagener Ricardo Oyarzún Victor Parra 《水文研究》2016,30(26):4934-4943
Groundwater storage, drainage, and interbasin water exchange are common hydrological processes but often difficult to quantify due to a lack of local observations. We present a study of three volcanic mountainous watersheds located in south‐central Chile (~36.9 ° S) in the Chillán volcanic complex (Chillán, Renegado, and Diguillín river basins). These are neighboring basins that are similar with respect to the metrics normally available for characterization everywhere (e.g., precipitation, temperature, and land cover). In a hydrological sense, similar (proportional) behavior would be expected if these catchments would be characterized with this general information. However, these watersheds show dissimilar behavior when analyzed in detail. The surface water balance does not fit for any of these watersheds individually; however, the water balance of the whole system can be explained by likely interbasin water exchanges. The Renegado river basin has an average annual runoff per unit of area on the order of 60–65% less than those of the Diguillín and Chillán rivers, which is contradictory to the hydrological similarity among the basins. To understand the main processes that control streamflow generation, two analyses were performed: (a) basin metrics (land cover, geologic, topographic, and climatological maps) and hydro‐meteorological data analyses and (b) a water balance model approach. The analyses contribute to a plausible explanation for the hydrogeological processes in the system. The soils, topography, and geology of the Chillán–Renegado–Diguillín system favor the infiltration and groundwater movements from the Renegado river basin, mainly to the neighboring Diguillín basin. The interbasin water exchanges affect hydrological similarity and explain the differences observed in the hydrological processes of these three apparently similar volcanic basins. The results highlight the complexity of hydrological processes in volcanic mountainous systems and suggest that a simple watershed classification approach based on widely available data is insufficient. Simple local analyses such as specific flow analysis with a review of the geology and morphology can contribute to a better understanding of the hydrology of volcanic mountainous areas. 相似文献
3.
To evaluate and measure the effectiveness of active control schemes in reducing the response of structures subjected to earthquake excitations, it is common to use recorded or artificially generated earthquakes as input motions. This paper introduces the response spectrum analysis to evaluate linear control systems for seismic inputs defined by code‐prescribed or site‐specific ground response spectra. Using such a method one can evaluate a control system in a single analysis for the ensemble of time histories that are represented by the input response spectra. The response spectrum analysis can also facilitate the implementation of comprehensive parametric studies. A generalized response spectrum method is used to analyse systems with non‐symmetrical matrices that are caused by the general nature of the control actions imposed on the structure. The application of the method is demonstrated on several numerical examples of a building structure where the control force is applied through an active tuned‐mass damper. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
4.
Enrique Gómez-Treviño Francisco Javier Esparza Hernández José Manuel Romo Jones 《Geofísica Internacional》2013,52(2):135-152
The series and parallel impedances of the magnetotelluric tensor are appraised in relation to their relative immunity to galvanic electric distortions. The distorted responses are modeled using the Groom-Bailey decomposition of the tensor in terms of twist, shear, statics and strike direction. These four parameters and the undistorted responses are normally considered as unknowns, and are obtained from field data through the solution of an inverse problem. In the present work we use the decomposition as a forward model to simulate distorted sounding curves. Starting with undistorted 2-d te and tm responses, the tensor is distorted by assuming arbitrary values of twist, shear, static and strike direction. By default, both series and parallel responses are immune to the strike direction because they are invariants under rotation. In addition, series responses are immune to twist and shear and parallel responses only to twist. The dependence of the latter on shear is in the form of a real factor that shifts downwards the amplitude curves. On the other hand, the effect of statics on both series and parallel responses is more complicated than that on the impedance tensor because it cannot be accounted for by a simple shift of the curves. On the whole, there is a positive balance on the part of the series and parallel impedances over the te and tm responses because some of the distortions are filtered out by the invariants. It is shown that invariance is not sufficient to be immune to any of the distortions. The example chosen is Eggers’ eigenvalues, which are immune only to the by-the-fault strike direction. Invariance is not necessary either, as evidenced by the phase tensor, whose elements depend on strike but are immune to all distortions. The derivations are illustrated using soundings from the synthetic coprod2s1 and field-recorded coprod2 and bc87 data sets. 相似文献
5.
A modified DRASTIC model for Siting Confined Animal Feeding Operations in Williams County,Ohio, USA 总被引:1,自引:0,他引:1
Three of DRASTIC’s parameters (Depth to Water, Soil Media, and Topography) were modified and another parameter was added (land
use/land cover) to the model to determine the potential impact on groundwater from Confined Animal Feeding Operations (CAFO)
manure lagoon settings and manure application as fertilizer. Williams County is a mostly agricultural county located in northwest
Ohio, USA. It currently has three CAFOs, all dairy, with the possibility of the construction of a multi-million chicken egg
CAFO in the near future. A Geographic Information System (GIS) was utilized to modify the Ohio Department of Natural Resources
(ODNR) DRASTIC map for the county to fully assess the county-wide pollution potential of CAFOs. The CAFO DRASTIC map indicates
that almost half of Williams County has elevated groundwater pollution potential. The rest of the county, primarily the southeast
corner, has lower CAFO groundwater pollution potential. Future CAFO development within the county should focus on the southeastern
portion of the county where the groundwater table is deeper, and the aquifer is composed of shale substrate with low hydraulic
conductivity. The CAFO DRASTIC results are intended to be used as a screening tool and are not to replace site-specific hydrogeologic
investigations. 相似文献
6.
7.
The paper presents a detailed reexamination of the effects of three damping models on the inelastic seismic response of structures with massless degrees of freedom. The models considered correspond to (a) Rayleigh damping based on current properties (tangent stiffness), (b) Rayleigh damping based on initial properties, and (c) modal damping. The results suggest that some nonzero damping forces/moments at massless DOFs obtained in multistory frames for the case of Rayleigh damping with tangent stiffness may be numerical artifacts rather than a deficiency of the damping model. The results also indicate that significant artificial numerical oscillations in the velocities of the secondary components of MDOF structures are introduced when modal damping or mass-proportional damping is used. 相似文献
8.
9.
Crustacean decapod assemblages associated with fragmented Posidonia oceanica meadows in the Alboran Sea (Western Mediterranean Sea): composition,temporal dynamics and influence of meadow structure 下载免费PDF全文
Ángel Mateo‐Ramírez Javier Urra Pablo Marina José L. Rueda José Enrique García Raso 《Marine Ecology》2016,37(2):344-358
The decapod assemblage associated with a Posidonia oceanica meadow located near its western limit of biogeographic distribution was studied over an annual cycle. Fauna samples were taken seasonally over a year (five replicates per season) in two sites located 7 km apart, using a non‐destructive sampling method (airlift sampler) for the seagrass. The dominant species of the assemblage, Pisidia longimana, Pilumnus hirtellus and Athanas nitescens, were associated with the protective rhizome stratum, which is mainly used as a nursery. The correlations between decapod assemblage structure and some phenological parameters of the seagrass shoots and wave height were negative or null, which reflects that species associated with the rhizome had a higher importance than those associated with the leaf stratum. The abundance and composition of the decapod assemblage as well as the ecological indexes displayed a seasonality trend with maximum values in summer‐autumn and minimum in winter‐spring, which were related to the seawater temperature and the recruitment periods of the dominant species. The spatial differences found in the structure and dynamics of the assemblages may be due to variations in the recruitment of the dominant species, probably as a result of the influence of local factors (e.g. temperature, currents) and the high dispersal ability of decapods, together with the patchy configuration and the surrounding habitats. The studied meadows are fragmented and are integrated within a mosaic of habitats (Cymodocea nodosa patches, algal meadows, rocky and sandy bottoms), which promotes the movement of individuals and species among them, maintaining a high species richness and evenness. 相似文献
10.
Enrique Pérez Richard de Grijs Rosa M. González Delgado 《Astrophysics and Space Science》2009,324(2-4):79-81