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201.
The viability of a complete structural characterization of civil structures is explored and discussed. In particular, the identification of modal (i.e. natural frequencies, damping ratios and modal shapes) and physical properties (i.e. mass and stiffness) using only the structure’s free decay response is studied. To accomplish this, modal analysis from free vibration response only (MAFVRO) and mass modification (MM) methodologies are engaged along with Wavelet based techniques for optimal signal processing and modal reconstruction. The methodologies are evaluated using simulated and experimental data. The simulated data are extracted from a simple elastic model of a 5 story shear building and from a more realistic nonlinear model of a RC frame structure. The experimental data are gathered from shake table test of a 2-story scaled shear building. Guidelines for the reconstruction procedure from the data are proposed as the quality of the identified properties is shown to be governed by adequate selection of the frequency bands and optimal modal shape reconstruction. Moreover, in cases where the structure has undergone damage, the proposed identification scheme can also be applied for preliminary assessment of structural health. 相似文献
202.
Anisotropic visco-hypoplasticity 总被引:5,自引:5,他引:0
Andrzej Niemunis Carlos Eduardo Grandas-Tavera Luis Felipe Prada-Sarmiento 《Acta Geotechnica》2009,4(4):293-314
Apart from time-driven creep or relaxation, most viscoplastic models (without plastic and viscous strain separation) generate
no or a very limited accumulation of strain or stress due to cyclic loading. Such pseudo-relaxation (or pseudo-creep) is either
absent or dwindles too fast with increasing OCR. For example, the accumulation of the pore water pressure and eventual liquefaction
due to cyclic loading cannot be adequately reproduced. The proposed combination of a viscous model and a hypoplastic model
can circumvent this problem. The novel visco-hypoplasticity model presented in the paper is based on an anisotropic preconsolidation
surface. It can distinguish between the undrained strength upon triaxial vertical loading and horizontal loading. The strain-induced
anisotropy is described using a second-order structure tensor. The implicit time integration with the consistent Jacobian
matrix is presented. For the tensorial manipulation including numerous Fréchet derivatives, a special package has been developed
within the algebra program MATHEMATICA (registered trade mark of Wolfram Research Inc.). The results can be conveniently coded using a special FORTRAN 90 module for tensorial operations. Simulations of element tests from biaxial apparatus and FE calculations are also shown. 相似文献
203.
The Open-source Project for a Network Data Access Protocol (OPeNDAP) software framework has evolved over the last 10 years to become a robust, high performance, service oriented architecture for the access and transport of scientific data from a broad variety of disciplines, over the Internet. Starting with version 4.0 of the server release, Hyrax, has at its core, the Back-End Server (BES). The BES offers ease of programming, extensibility and reliability allowing added functionality especially related to high-performance data Grids, that goes beyond its original goal of distributed data access. We present the fundamentals of the BES server as a component based architecture, as well as our experiences using the BES to distribute data processing in Grid-oriented intensive parallel computational tasks. 相似文献
204.
Siham Tabik Luis Felipe Romero Emilio López Zapata 《International journal of geographical information science》2013,27(4):541-555
This work presents a high-performance algorithm to compute the horizon in very large high-resolution DEMs. We used Stewart's algorithm as the core of our implementation and considered that the horizon has three components: the ground, near, and far horizons. To eliminate the edge-effect, we introduced a multi-resolution halo method. Moreover, we used a new data partition approach, to substantially increase the parallelism in the algorithm. In addition, several optimizations have been applied to considerably reduce the number of arithmetical operations in the core of the algorithm. The experimental results have demonstrated that by applying the above-described contributions, the proposed algorithm is more than twice faster than Stewart's algorithm while maintaining the same accuracy. 相似文献
205.
Pablo Otero Manuel Ruiz-Villarreal Luz García-García Gonzalo González-Nuevo Jose Manuel Cabanas 《Ocean Dynamics》2013,63(1):115-129
The consequences of a stormy winter period (2009/2010) on the shelf and coastal dynamics off Northwest Iberia are analysed by using model results in combination with the set of available observations in the frame of the Iberian Margin Ocean Observatory (RAIA), a cross-border infrastructure among North Portugal and Galicia (Spain). During the study winter, the frequent arrival of weather fronts forced river plumes to flow along the inner shelf in a fast (>1 m?s?1) jet-like structure. The buoyant current strongly influenced the outer rías, the name of the estuaries in the region, where a strong decay of surface salinity (<10.5) has been observed. Once the weather front has passed, the wind reversal forced the offshore expansion of river plumes and also the development of a winter upwelling event. Thermohaline patterns in both model and observations revealed an intrusion of warm (>15 °C) and salty (>35.9) waters into the rías associated with the Iberian Poleward Current. Finally, some Lagrangian modelling experiments were performed to analyse the transport ability of the plume and the effect that could have had in the biological material trapped on it. The experiments reveal that an overall northward displacement of surface particles will be expected after several alternate wind events. 相似文献
206.
Jose A. Carnicero M. Concepción Ausín Michael P. Wiper 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(8):1991-2002
This paper proposes a nonparametric approach to estimating the dependence relationships between circular variables and other circular or linear variables using copulas. The proposed method is based on the use of Bernstein copulas which are a very flexible class of non-parametric copulas which allows for the approximation of any kind of dependence structure, including non symmetric relationships. In particular, we present a simple procedure to adapt Bernstein copulas to the circular framework and guarantee that the constructed bivariate distributions are strictly continuous. We provide two illustrative case studies, the first on the relation between wind direction and quantity of rainfall in the North of Spain and the second on the dependence between the wind directions in two nearby buoys at the Atlantic ocean. 相似文献
207.
In this study we analyze water level data from coastal tide gauges and deep-ocean tsunameters to explore the far-field characteristics of two major trans-Pacific tsunamis, the 2010 Chile and the 2011 Japan (Tohoku-oki) events. We focused our attention on data recorded in California (14 stations) and New Zealand (31 stations) as well as on tsunameters situated along the tsunami path and proximal to the study sites. Our analysis considers statistical analyses of the time series to determine arrival times of the tsunami as well as the timing of the largest waves and the highest absolute sea levels. Fourier and wavelet analysis were used to describe the spectral content of the tsunami signal. These characteristics were then compared between the two events to highlight similarities and differences between the signals as a function of the receiving environment and the tsunami source. This study provides a comprehensive analysis of far-field tsunami characteristics in the Pacific Ocean, which has not experienced a major tsunami in nearly 50 years. As such, it systematically describes the tsunami response characteristics of modern maritime infrastructure in New Zealand and California and will be of value for future tsunami hazard assessments in both countries. 相似文献
208.
Yolanda Cantón Luis Villagarcía María José Moro Penelope Serrano-Ortíz Ana Were Francisco Javier Alcalá 《水文科学杂志》2013,58(5):737-753
Abstract This paper analyses the temporal dynamics of soil water balance components in a representative recharge area of the Sierra de Gádor (Almeria, southeastern Spain) in two hydrological years. Two approaches are used to estimate daily potential recharge (PR): Approach 1 based on deriving PR from the water balance as the difference between measurements of rainfall (P) and actual evapotranspiration (E) obtained by eddy covariance; and Approach 2 with PR obtained from the dynamic pattern of the soil moisture (θ) recorded at two depths in the site's thin soil (average 0.35 m thickess). For the hydrological year 2003/04, which was slightly drier than the 30-year average, E accounted for 64% of rainfall and occurred mainly in late spring and early summer. The PR estimated by Approach 1 was 181 ± 18 mm year-1 (36% of rainfall), suggesting an effective groundwater recharge in the study area. In the unusually dry hydrological year 2004/05, E was about 215 mm year-1, close to the annual rainfall input, and allowing very little (8 ± 12 mm year-1) PR according to Approach 1. Estimation of PR based on Approach 2 resulted in PR rates lower than those found by Approach 1, because Approach 2 does not take into account the recharge that occurs through preferential flow pathways (cracks, joints and fissures) which were not monitored with the θ probes. Moreover, using Approach 2, the PR estimates differed widely depending on the time scale considered: with daily mean θ data, PR estimation was lower, especially in late spring, while θ data at 30 min resolution yielded a more reliable prediction of the fraction of total PR resulting from the downward movement of soil water by gravity. Citation Cantón, Y., Villagarcía, L., Moro, M. J., Serrano-Ortíz, P., Were, A., Alcalá, F. J., Kowalski, A. S., Solé-Benet, A., Lázaro, R. & Domingo, F. (2010) Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge. Hydrol. Sci. J. 55(5), 737–753. 相似文献
209.
AbstractThe Hilhorst model was used to convert bulk electrical conductivity (σb) to pore water electrical conductivity (σp) under laboratory conditions by using the linear relationship between the soil dielectric constant (εb) and σb. In the present study, applying the linear relationship εb–σb to data obtained from field capacitance sensors resulted in strong positive autocorrelations between the residuals of that regression. We were able to derive an accurate offset of the relationship εb–σb and to estimate the evolution of σp over time by including a stochastic component to the linear model, rearranging it to a time-varying dynamic linear model (DLM), and using Kalman filtering and smoothing. The offset proved to vary for each depth in the same soil profile. A reason for this might be the changes in soil temperature along the soil profile.
Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus 相似文献
210.
We applied analysis AVO with partial stacking to an onshore gas field in order to detect gas at the top of the Ciénaga de Oro formation (FCO), by using seismic gathers of the Güepajé-3D project. The technique was supported by petrophysical analysis of the Ayombe-1 well.The sensitivity of seismic response to changes in the saturating fluid was evaluated by fluid substitution technique in an interval of the Ayombe-1 well. As a result, a class I AVO anomaly at the top of the FCO was observed, even though the gas and water responses were similar. After applying AVO with partial stack technique at the top of FCO, AVO class I anomalies were observed in the Ayombe-1 and Güepajé-1 gas wells and none in the dry Güepajé-3 well. In spite of being reported with gas, the results in the Güepajé-2 well indicated any to an incipient class I anomaly related to a weak seismic response associated to gas.When the technique was applied to the seismic volume of the Güepajé-3D Project, a map of the direct gas indicator was obtained. The map shows a high correlation with the structural surface at top of FCO. Lithic factors such as compaction, cementation and carbonate overlaying the FCO and variable thickness of partial and full saturated layers, may cause anomalies in zones unlikely to contain gas. 相似文献