Physically-based prediction of the maximum corner displacement magnification of one-storey eccentric systems     

Michele Palermo  Stefano Silvestri  Giada Gasparini  Tomaso Trombetti 《Bulletin of Earthquake Engineering》2013,11(5):1467-1491

This paper gives a new insight into the linear dynamic behavior of one-storey eccentric systems, with particular attention devoted to provide a comprehensive physically-based formulation of the maximum corner displacement magnification, which involves three contributions (translational response, torsional response and their combination). It is shown that the largest magnifications, which mainly occur for the class of torsionally-flexible systems, are due to the translational contribution which is caused by the shift of the fundamental period of the eccentric system with respect to that of the equivalent not-eccentric system. A simplified method for the estimation of the maximum corner displacement under seismic excitation, based on the physical properties of the eccentric system, is finally proposed.  相似文献   

Investigating prediction performance of an artificial neural network and a numerical model of the tidal signal at Puerto Belgrano, Bahia Blanca Estuary (Argentina)     

Jorge O. Pierini  Michele Lovallo  Luciano Telesca  Eduardo A. Gómez 《Acta Geophysica》2013,61(6):1522-1537

In the present study we compare performances of the prediction of hourly tidal level variations at Puerto Belgrano, a coastal site in the Bahia Blanca Estuary (Argentina), by means of the MOHID model, which is a numerical model designed for coastal and estuarine shallow water applications, and of an artificial neural network (ANN). It was shown that the ANN model is able to predict the hourly tidal levels over long term duration with at least seven days of observations and with a better performance in respect to the numerical model. Our findings can be useful to implement ANN-based tools for future studies of the hydrodynamics of Bahía Blanca estuary.  相似文献   

Uncertainty and sensitivity analysis: tools for GIS-based model implementation     

Michele Crosetto  Stefano Tarantola 《International journal of geographical information science》2013,27(5):415-437

A novel procedure to analyse the uncertainty associated to the output of GIS-based models is presented. The procedure can handle models of any degree of complexity that accept any kind of input data. Two important aspects of spatial modelling are addressed: the propagation of uncertainty from model inputs and model parameters up to the model output (uncertainty analysis); and the assessment of the relative importance of the sources of uncertainty in the output uncertainty (sensitivity analysis). Two main applications are proposed. The procedure allows implementation of a GIS-based model whose output can reliably support the decision process with an optimized allocation of resources for spatial data acquisition. This is possible in low cost strategy, based on numerical simulations on a small prototype of the GIS-based model. Furthermore, the procedure provides an effective model building tool to choose, from a group of alternative models, the best one in terms of cost-benefit analysis. A comprehensive case study is described. It concerns the implementation of a new GIS-based hydrologic model, whose goal is providing near real-time flood forecasting.  相似文献   

Model complexity and data requirements in snow hydrology: seeking a balance in practical applications          下载免费PDF全文

Francesco Avanzi  Carlo De Michele  Samuel Morin  Carlo Maria Carmagnola  Antonio Ghezzi  Yves Lejeune 《水文研究》2016,30(13):2106-2118

We investigate the problem of balancing model complexity and input data requirements in snow hydrology. For this purpose, we analyze the performance of two models of different complexity in estimating variables of interest in snow hydrology applications. These are snow depth, bulk snow density, snow water equivalent and snowmelt run‐off. We quantify the differences between data and model prediction using 18 years of measurements from an experimental site in the French Alps (Col de Porte, 1325 m AMSL). The models involved in this comparison are a one‐layer temperature‐index model (HyS) and a multilayer model (Crocus). Results show that the expected loss in performance in the one‐layer temperature‐index model with respect to the multilayer model is low when considering snow depth, snow water equivalent and bulk snow density. As for run‐off, the comparison returns less clear indications for identification of a balance. In particular, differences between the models' prediction and data with an hourly resolution are higher when considering the Crocus model than the HyS model. However, Crocus is better at reproducing sub‐daily cycles in this variable. In terms of daily run‐off, the multilayer physically based model seems to be a better choice, while results in terms of cumulative run‐off are comparable. The better reproduction of daily and sub‐daily variability of run‐off suggests that use of the multilayer model may be preferable for this purpose. Variation in performance is discussed as a function of both the calibration solution chosen and the time of year. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Using the Fisher–Shannon method to characterize continuous seismic signal during volcanic eruptions: application to 2011–2012 El Hierro (Canary Islands) eruption     

Luciano Telesca  Michele Lovallo  Joan Martì Molist  Carmen López Moreno  Rafael Abella Meléndez 《地学学报》2014,26(6):425-429

We investigated the dynamics of the continuous seismic signal recorded before and during the 2011–2012 El Hierro eruption (Canary Islands) using the innovative approach of the Fisher–Shannon method, a suitable statistical tool for detecting dynamic changes in complex systems. Our findings identify dynamic changes in the seismic signal that can be correlated with different stress states of the magmatic setting and the plumbing system in the volcano at El Hierro. The results contribute to the understanding of the fracturing pattern in the crust during a new intrusion and eruption of an overpressurized batch of magma.  相似文献   

Evaporation and the subcanopy energy environment in a flooded forest          下载免费PDF全文

Scott T. Allen  Michele L. Reba  Brandon L. Edwards  Richard F. Keim 《水文研究》2017,31(16):2860-2871

The combination of tree canopy cover and a free water surface makes the subcanopy environment of flooded forested wetlands unlike other aquatic or terrestrial systems. Subcanopy vapour fluxes and energy budgets represent key controls on water level and understorey climate but are not well understood. In a permanently flooded forest in south‐eastern Louisiana, USA, an energy balance approach was used to address (a) whether evaporation from floodwater under a forest canopy is solely energy limited and (b) how energy availability was modulated by radiation and changes in floodwater heat storage. A 5‐month continuous measurement period (June–November) was used to sample across seasonal changes in canopy activity and temperature regimes. Over this period, the subcanopy airspace was humid, maintaining saturation vapour pressure for 28% of the total record. High humidity coupled with the thermal inertia of surface water altered both seasonal and diel energy exchanges, including atypical phenomena such as frequent day‐time vapour pressure gradients towards the water surface. Throughout the study period, nearly all available energy was partitioned to evaporation, with minimal sensible heat exchange. Monthly mean evaporation ranged from 0.7 to 1.7 mm/day, peaking in fall when canopy senescence allowed greater radiation transmission; contemporaneous seasonal temperature shifts and a net release of stored heat from the surface water resulted in energy availability exceeding net radiation by 30% in October and November. Relatively stable energy partitioning matches Priestley–Taylor assumptions for a general model of evaporation in this ecosystem.  相似文献   

Landslide risk perception: a case study in Southern Italy   总被引：2，自引：0，他引：2  

Michele Calvello  Maria Nicolina Papa  Jonathan Pratschke  Maria Nacchia Crescenzo 《Landslides》2016,13(2):349-360

Perceptions of risk are a key issue when seeking to develop systems, practices and policies to protect local populations. This is particularly evident when risk mitigation strategies involve non-structural measures such as relocation and warning systems which presuppose the active involvement of the communities in question. This study adopts an interdisciplinary approach to studying the perceptions, knowledge and opinions on landslide risk amongst residents in Sarno, a small town in Southern Italy which was hit by disastrous landslides on 5–6 May 1998. The paper presents the results of a survey conducted in the months of March, April and May 2013 using a purpose-designed questionnaire. The survey was conducted using face-to-face interviews with 100 residents, 60 of whom live inside the so-called “red zone”, a territory declared at high residual risk soon after the events of 1998. The questionnaire included questions relating to perceived risk exposure, trust in institutions responsible for risk management, evaluations of risk mitigation measures and the early-warning strategy. The results of the study clearly emerges, amongst other issues, that the organisms which are responsible for risk management in Sarno need to develop more effective communication strategies in order to transmit knowledge about the actions implemented to reduce landslide risk in the area.  相似文献   

The role of ground reference data collection in the prediction of stem volume with LiDAR data in mountain areas     

Michele Dalponte  Cristina Martinez  Mirco Rodeghiero  Damiano Gianelle 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(6):787-797

Ground reference data collection represents an important element in the prediction of stem volume with LiDAR-derived variables, and at present it is the most expensive part of such analyses. In this paper two aspects of ground reference data collection were analyzed: (1) the positioning error of the ground plots; and (2) the optimal number of training plots. A system for the prediction of stem volume at area-based level was adopted. LiDAR data were preprocessed and 13 variables describing both height and coverage were extracted. Models were defined using a stepwise ordinary least square (OLS) regression. Three experiments were conducted: (i) the role of the plots positioning error on prediction accuracy; (ii) the influence of random downsampling of plot numbers on prediction accuracy; and (iii) the influence of a stratified downsampling of plot numbers on prediction accuracy based on LiDAR-derived variables. A dataset comprising 799 ground plots was used. They were distributed throughout a mountainous area in the Southern Alps, where the presence of a complex landscape increases the uncertainty of the Global Positioning System (GPS) accuracy, and where a large variety of tree forest species and climatic environments make it necessary to have a large number of sample plots for accurate characterization of the study area. All the experiments provided important indications for LiDAR based forest inventories: the GPS error did not significantly influence the prediction accuracy and it was possible to reduce the number of training samples without compromising the generalization ability of the prediction model. Leading on from these findings, a new ground sampling protocol based on genetic algorithms was proposed. The new protocol allowed us to obtain promising results for the considered dataset: using only 53 training plots, instead of 534 in the original dataset, we obtained the same results for the validation set. These results, obtained in a complex mountainous area, are representative of Alpine environments and allow us to infer that similar (or better) results could also be obtained within non mountainous areas.  相似文献   

Aerodynamic Roughness Length of Fresh Snow   总被引：1，自引：1，他引：0  

Christof Gromke  Costantino Manes  Benjamin Walter  Michael Lehning  Michele Guala 《Boundary-Layer Meteorology》2011,141(1):21-34

This study presents the results from a series of wind-tunnel experiments designed to investigate the aerodynamic roughness length z ₀ of fresh snow under no-drift conditions. A two-component hot-film anemometer was employed to obtain vertical profiles of velocity statistics in a zero pressure gradient turbulent boundary layer for flow over naturally deposited snow surfaces. The roughness of these snow surfaces was measured by means of digital photography to capture characteristic length scales that can be related to z ₀. Our results show that, under aerodynamically rough conditions, the mean value of the roughness length for fresh snow is \({\langle{z}_{0}\rangle= 0.24}\) mm with a standard deviation σ(z ₀) = 0.05 mm. In this study, we show that variations in z ₀ are associated with variations in the roughness geometry. The roughness measurements suggest that the estimated values of z ₀ are consistent with the presence of irregular roughness structures that develop during snowfalls that mimic ballistic deposition processes.  相似文献   

The Sage handbook of social geographies – Edited by Susan J. Smith,Rachel Pain,Sallie A. Marston and John Paul Jones III     

Michele Lobo 《New Zealand geographer》2011,67(1):63-64

  相似文献