Some remarks on the assessment of P-wave velocity in laboratory tests for evaluating the degree of saturation     

Astuto  Giuseppe  Molina-Gómez  Fausto  Bilotta  Emilio  Viana da Fonseca  António  Flora  Alessandro 《Acta Geotechnica》2023,18(2):777-790

Acta Geotechnica - This work stems from the need to validate a technique for a reliably measurement of the degree of saturation (Sr) in deposits composed of sandy soils to improve their...  相似文献   

Climatic and Tidal Forcing of Hydrography and Chlorophyll Concentrations in the Columbia River Estuary     

G. Curtis Roegner  Charles Seaton  António M. Baptista 《Estuaries and Coasts》2011,34(2):281-296

Hydrographic patterns and chlorophyll concentrations in the Columbia River estuary were compared for spring and summer periods during 2004 through 2006. Riverine and oceanic sources of chlorophyll were evaluated at stations along a 27-km along-estuary transect in relation to time series of wind stress, river flow, and tidal stage. Patterns of chlorophyll concentration varied between seasons and years. In spring, the chlorophyll distribution was dominated by high concentrations from freshwater sources. Periods of increased stream flow limited riverine chlorophyll production. In summer, conversely, upwelling winds induced input of high-salinity water from the ocean to the estuary, and this water was often associated with relatively high chlorophyll concentrations. The frequency, duration, and intensity of upwelling events varied both seasonally and interannually, and this variation affected the timing and magnitude of coastally derived material imported to the estuary. The main source of chlorophyll thus varied from riverine in spring to coastal in summer. In both spring and summer seasons and among years, modulation of the spring/neap tidal cycle determined stratification, patterns of mixing, and the fate of (especially freshwater) phytoplankton. Spring tides had higher mixing and neap tides greater stratification, which affected the vertical distribution of chlorophyll. The Columbia River differs from the more tidally dominated coastal estuaries in the Pacific Northwest by its large riverine phytoplankton production and transfer of this biogenic material to the estuary and coastal ocean. However, all Pacific Northwest coastal estuaries investigated to date have exhibited advection of coastally derived chlorophyll during the upwelling season. This constitutes a fundamental difference between Pacific Northwest estuaries and systems not bounded by a coastal upwelling zone.  相似文献   

Out‐of‐plane behaviour of a full scale stone masonry façade. Part 1: specimen and ground motion selection     

Alexandre A. Costa  António Arêde  Alfredo Campos Costa  Andrea Penna  Aníbal Costa 《地震工程与结构动力学》2013,42(14):2081-2095

The out‐of‐plane response of walls in existing stone masonry buildings is one of the major causes of vulnerability commonly observed in post‐earthquake damage surveys. In this context, a shaking table (ST) test campaign was carried out on a full‐scale masonry façade mainly focusing on the characterization of its out‐of‐plane overturning behaviour. The structure tested on the ST is a partial reproduction of an existing building from Azores, damaged during the 9 July 1998 Faial earthquake. The definition of the tested specimen as well as the selection of the input ground motion is reported in this paper. A specific emphasis is given to the definition of the time‐history to be applied during the tests because it was felt as an essential and crucial part of the work to obtain the desired overturning behaviour. The accelerogram to be imposed was selected from a large set of accelerograms (74) by means of a step‐by‐step procedure on the basis of several numerical analyses resorting to the rocking response of rigid blocks. A companion paper (Part 2) focuses on the ST test results and detailed data interpretation. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Paying as the urban areas grow – implementing and managing urban development charges using a GIS application     

Jorge Baptista e Silva  Raquel Faria de Deus  José António Tenedório 《International journal of geographical information science》2013,27(9):1689-1705

Urban development charges (UDC) are considered relevant taxation instruments that can improve the economic sustainability of urban areas and the financial health of the respective local governments. The economic formulation and justification based on the ‘direct benefit principle,’ the ‘accountability principle,’ and the ‘proportionality principle’ requires a methodology that can be supported by a geographic information system (GIS) application. This article presents the research output of a real case study – the municipality of Aljezur, Portugal – and the fundamentals of the GIS tool that was designed. This GIS-based methodology comprises a multi-annual infrastructure capital plan and an accurate zoning map for spatial differentiation of values combining municipal-wide and site-specific approaches, following ‘pay as the urban areas grow’ perspective applied to urban development and new buildings. It requires data integration of the urban planning process with infrastructure and urban growth data in order to manage and monitor the computation of this charge over time, thereby increasing the accuracy, the objectivity and the clarity of the process. The results obtained show that this UDC-GIS application seems well adapted to small municipalities. Its possible replication and use in other contexts require adaptations derived from different urban and taxation policy options and from different legal, organizational, technological, and informational local systems.  相似文献   

Do the recent severe droughts in the Amazonia have the same period of length?     

Yong Zou  Elbert E. N. Macau  Gilvan Sampaio  Antônio M. T. Ramos  Jürgen Kurths 《Climate Dynamics》2016,46(9-10):3279-3285

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Cyclic and Dynamic Behavior of Sand–Rubber and Clay–Rubber Mixtures     

Rios  Sara  Kowalska  Magdalena  Viana da Fonseca  António 《Geotechnical and Geological Engineering》2021,39(5):3449-3467

Geotechnical and Geological Engineering - In this paper, the possibility of using fine scrap tyre rubber to improve the mechanical properties of soil subjected to cyclic loading is...  相似文献   

Confidence levels for tsunami-inundation limits in northern Oregon inferred from a 10,000-year history of great earthquakes at the Cascadia subduction zone   总被引：1，自引：1，他引：0  

George R. Priest  Chris Goldfinger  Kelin Wang  Robert C. Witter  Yinglong Zhang  António M. Baptista 《Natural Hazards》2010,54(1):27-73

To explore the local tsunami hazard from the Cascadia subduction zone we (1) evaluate geologically reasonable variability of the earthquake rupture process, (2) specify 25 deterministic earthquake sources, and (3) use resulting vertical coseismic deformations for simulation of tsunami inundation at Cannon Beach, Oregon. Maximum runup was 9–30 m (NAVD88) from earthquakes with slip of ~8–38 m and M _w ~8.3–9.4. Minimum subduction zone slip consistent with three tsunami deposits was 14–15 m. By assigning variable weights to the source scenarios using a logic tree, we derived percentile inundation lines that express the confidence level (percentage) that a Cascadia tsunami will not exceed the line. Ninety-nine percent of Cascadia tsunami variation is covered by runup ≤30 m and 90% ≤16 m with a “preferred” (highest weight) value of ~10 m. A hypothetical maximum-considered distant tsunami had runup of ~11 m, while the historical maximum was ~6.5 m.  相似文献   

Analysis of Factors Influencing Simulations of the 1993 Hokkaido Nansei-Oki and 1964 Alaska Tsunamis   总被引：3，自引：0，他引：3  

Edward P. Myers  António M. Baptista 《Natural Hazards》2001,23(1):1-28

The purpose of this paper is to examine factorsinfluencing numerical simulations of tsunamis, andtheir implications for hazard mitigation. We focus ona specific finite element hydrodynamic model, chosenfor its role in the systematic development ofinundation maps for regions threatened primarily byCascadia Subduction Zone (CSZ) tsunamis. However, inpart for generality and in part because of poorhistorical records for CSZ events, we discuss here theperformance of the model in the context of betterdocumented past events with epicenters locatedelsewhere: the July 12, 1993 Hokkaido Nansei-Oki andthe March 28, 1964 Alaska tsunamis. Our analysisincludes the influence of grid refinement,interactions between tides and tsunamis, artificialenergy loss, and numerical parameterization. We showthat while the ability exists to reproduce pastevents, limitations remain in the modeling processthat should be accounted for in translating modelingresults into information for tsunami mitigation andresponse.  相似文献   

Theoretical considerations of meandering winds in simplified conditions     

Antônio G. O. Goulart  Gervásio A. Degrazia  Otávio C. Acevedo  Domenico Anfossi 《Boundary-Layer Meteorology》2007,125(2):279-287

The influence of turbulence on the meandering phenomenon is investigated. The study, based on the three-dimensional Navier–Stokes equations, shows that when the turbulent fluxes can be neglected an asymptotic solution results. This solution reproduces a horizontal wind oscillation with an infinite relaxation time. When there is turbulent forcing, on the other hand, a transition occurs to a new order, characterized by a spatial reorganization, leading to a wind field with a well-defined direction.  相似文献   

The University of Porto Radio Spectrograph     

António Magalhães  Jorge Carneiro 《Astrophysics and Space Science》1998,261(1-4):211-212

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