Artificial Intelligence Applications in Transportation Geotechnics   总被引：1，自引：1，他引：0  

A. Gomes Correia  P. Cortez  J. Tinoco  R. Marques 《Geotechnical and Geological Engineering》2013,31(3):861-879

This paper presents a brief overview of artificial intelligence applications in transportation geotechnics, highlighting new approaches and current research directions, including issues related to data mining interpretability and prediction capacities. Several practical applications to earthworks, including the compaction management and quality control aspects of embankments, as well as pavement evaluation, design and management, and the mechanical behaviour of jet grouting material, are presented to illustrate the advantages of using data mining, including artificial neural networks, support vector machines, and evolutionary computation techniques in this domain. This study also propose a novel simplified compaction table for reusing geomaterials and compaction management in embankments and applied one- and two-dimensional advanced sensitivity analyses to better interpret the proposed data-driven models for the prediction of the deformability modulus of jet grouting field samples. These applications show the capabilities of data mining models to address complex problems in transportation geotechnics involving highly nonlinear relationships of data and optimisation needs.  相似文献   

Tectonic evolution of the deep crust: Variscan reactivation by extension and thrusting of Precambrian basement in the Bragança and Morais massifs (Tras-os-Montes,NE Portugal)     

F.G. Marques  A. Ribeiro  E. Pereira 《Geodinamica Acta》2013,26(1-2):135-151

Abstract

The Braganca amd Morais Massifs (NE Portugal) comprise a pile of four nappes on lop of the Autochthon of the Central-Iberian Zone : a Parautochthon (PTC), a Lower Allochthon (LATC), an Ophiolitic Complex (OTC) and an Upper Allochton (UATC). This article focuses on the tectonic evolution of the prc-Variscan basement preserved in the Upper Allochthonous Thrust Complex. (1) In the Morais Massif, the UATC is mainly composed of orthogneisscs, micaschists and high-grade melamorphic rocks restricted to a small duplex between the orthogneisses and the ophiolitic complex. The orthogneisses are pervasively deformed by D6 (Variscan D1). characterized by NNW-SSE stretching lineation, C-S structures, and sense of shear to the SSE. The high-grade melamorphic rocks show at least three ductile deformation phases older than the gneisses deformation. The micaschists and the orthogneisses are cut by mafic sills and dykes transformed into amphibolites by the Variscan tec-tonometamorphic evolution. In a restricted domain where dykes arc less deformed, two deformation events can be recognized and arc considered to be pre-Variscan. The walls of the dykes show a N-S stretching and mineral lineation interpreted as resulting from D6 (Variscan D1). (2) In the Braganca Massif, the UATC comprises mafic to ultrainafic igneous and high-grade melamorphic rocks, and paragncisses with ky-eclogite lenses. Six ductile deformation phases are recognized. The D1 to D4 events may correspond to a complete pre-Variscan orogenic cycle, from subduction (D1) to collision (D2-DS) and thrusting of the high-grade metamorphic rocks to upper levels in the crust (D3-D4); D5 may result from the Lower Palaeozoic extensional event that marks the begining of the Variscan Wilson cycle; D6 is interpreted as the first Variscan orogenic event with southward movement. The UATC of the Cabo Ortegal anil Braganca Massifs comprise mainly upper mantle/lower erustal rocks. By contrast, the UATC of the Ordenes and Morais Massifs is mainly composed of middle to upper erustal rocks. Vic propose that this is the result of a regional ductile normal fault (extensional event) that was active prior to the Variscan orogeny, in Lower Palaeozoic times, and affected a Precambrian basement.  相似文献   

Packed‐Column of Granular Activated Carbons for Removal of Chemical Oxygen Demand from Industrial Wastewater     

Sawanya Laohaprapanon  Marcia Marques  Fabio Kaczala  William Hogland 《洁净——土壤、空气、水》2013,41(3):244-250

In the present study, chemical oxygen demand (COD) removal by packed‐columns of activated carbon (AC) derived from two different materials (coal activated carbon, CAC and wood activated carbon, WAC) is reported as part of an on‐site wastewater treatment system for handling small volumes of wastewater generated at wood‐floor industries for which there are no proper on‐site treatment options available in the market. The performance of the sorbents, the effect of bed depth (0.19 and 0.57 m) and volumetric load (0.10 and 0.24 m h^?1) on the breakthrough curve of sorption systems were studied. The results indicated the feasibility of using both ACs to treat these wastewaters. At the bed depth (0.57 m), volumetric load (0.24 m h^?1), and 30% breakthrough, CAC and WAC showed treatment capacity of 40.5 L kg^?1 in 250 h and 23.8 L kg^?1 in 63 h, respectively. This indicated that CAC requires longer retention times to reach a performance similar to WAC. The experimental data was fit into the bed depth‐service time model showing that under the same conditions, CAC had higher maximum sorption capacity (N₀) than WAC. Moreover, thermal regeneration at 500°C temperature could be a cost‐effective procedure since the reuse of spent AC through such regeneration process for further treatment could still achieve 90% of the initial sorption capacity, reducing then costs for the use of new sorbents and also the need for waste disposal.  相似文献   

Performance evaluation of retrofitting strategies for non-seismically designed RC buildings using steel braces   总被引：1，自引：1，他引：0  

H. Varum  F. Teixeira-Dias  P. Marques  A. V. Pinto  A. Q. Bhatti 《Bulletin of Earthquake Engineering》2013,11(4):1129-1156

Recent major earthquakes around the world have evidenced that research in earthquake engineering must be directed to the vulnerability assessment of existing constructions lacking appropriate seismic resisting characteristics. Their retrofit or replacement should be made in order to reduce vulnerability, and consequent risk, to currently accepted levels. In this work, the efficiency of ductile steel eccentrically-braced systems in the seismic retrofitting of existing reinforced concrete (RC) buildings is studied. The retrofit technique studied consists in a bracing system with an energy dissipation device, designed to dissipate energy by shear deformation. The numerical model was calibrated with cyclic test results on a full-scale structure. The models used for the RC frame and masonry represent their real behavior and influence in the global structural response. The steel bracing system was modeled with strut rigid elements. The model for the energy dissipater device reproduces rigorously the behavior of the shear-link observed in the cyclic tests, namely in terms of shear, drift and energy dissipation. With the calibrated numerical model, a series of non-linear dynamic analyses were performed, for different earthquake input motions, intending to study: the influence of the retrofitting system in the response of bare and infilled structures; the influence of the location and strength of the retrofitting system.  相似文献   

Overview and status of estuarine microphytobenthos ecological research in South Africa     

T Dalu  JB Adams  JC Taylor  GC Bate  M Nunes  PW Froneman 《African Journal of Marine Science》2018,40(1):1-12

This article presents a historical overview of estuarine microphytobenthos (MPB) research in South Africa published over the period 1950 to the present, highlighting major milestones, challenges and estuarine management problems, as well as future research needs within the South African context. The studies that were covered comprise peer-reviewed books and journal articles on relevant research conducted in any estuarine environment during the period reviewed. There was a general increase in MPB research outputs over the decades, from only two publications in the 1950s, to over 20 outputs between 2010 and the present. Whereas the MPB studies in South Africa cover a broad spectrum of themes, the research priorities in these works have changed from taxonomically biased studies to those of ecologically based research. Research in the 1950s and 1960s was exclusively taxonomic in nature, with the first ecological investigation incorporating MPB being produced in the 1970s. By the 1980s, ecological studies dominated the research outputs and this trend has persisted to the present. The 1990s and 2000s saw the rise of research into the role of fresh water as a driver of MPB dynamics, whereas the period 2010 to the present saw an increase in more diverse ecological themes, ranging from an autecological investigation to food-web studies and the assessment of multiple drivers of MPB dynamics. However, the majority of studies have focused on either diatoms or estimates of overall MPB biomass. Moreover, there is a regional underrepresentation that runs broadly along biogeographic lines, with the bulk of the work having been conducted in the warm-temperate and subtropical zones of South Africa. Challenges and future research needs for the region are outlined, as is the need to expand MPB research to include other aspects of the biology and ecology of this flora.  相似文献   

On the treatment of uncertainties in the development of fragility functions for earthquake loss estimation of building portfolios          下载免费PDF全文

Luis Sousa  Vitor Silva  Mário Marques  Helen Crowley 《地震工程与结构动力学》2016,45(12):1955-1976

State‐of‐the‐art methods for the assessment of building fragility consider the structural capacity and seismic demand variability in the estimation of the probability of exceeding different damage states. However, questions remain regarding the appropriate treatment of such sources of uncertainty from a statistical significance perspective. In this study, material, geometrical and mechanical properties of a number of building classes are simulated by means of a Monte Carlo sampling process in which the statistical distribution of the aforementioned parameters is taken into consideration. Record selection is performed in accordance with hazard‐consistent distributions of a comprehensive set of intensity measures, and issues related with sufficiency, efficiency, predictability and scaling robustness are addressed. Based on the appraised minimum number of ground motion records required to achieve statistically meaningful estimates of response variability conditioned on different levels of seismic intensity, the concept of conditional fragility functions is presented. These functions translate the probability of exceeding a set of damage states as a function of a secondary sufficient intensity measure, when records are selected and scaled for a particular level of primary seismic intensity parameter. It is demonstrated that this process allows a hazard‐consistent and statistically meaningful representation of uncertainty and correlation in the estimation of intensity‐dependent damage exceedance probabilities. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A Variable Mesh Spacing for Large-Eddy Simulation Models in the Convective Boundary Layer     

Gervásio Annes Degrazia  Umberto Rizza  Franciano Scremin Puhales  Antônio Gledson Goulart  Jonas Carvalho  Guilherme Sausen Welter  Edson Pereira Marques Filho 《Boundary-Layer Meteorology》2009,131(2):277-292

A variable vertical mesh spacing for large-eddy simulation (LES) models in a convective boundary layer (CBL) is proposed. The argument is based on the fact that in the vertical direction the turbulence near the surface in a CBL is inhomogeneous and therefore the subfilter-scale effects depend on the relative location between the spectral peak of the vertical velocity and the filter cut-off wavelength. From the physical point of view, this lack of homogeneity makes the vertical mesh spacing the principal length scale and, as a consequence, the LES filter cut-off wavenumber is expressed in terms of this characteristic length scale. Assuming that the inertial subrange initial frequency is equal to the LES filter cut-off frequency and employing fitting expressions that describe the observed convective turbulent energy one-dimensional spectra, it is feasible to derive a relation to calculate the variable vertical mesh spacing. The incorporation of this variable vertical grid within a LES model shows that both the mean quantities (and their gradients) and the turbulent statistics quantities are well described near to the ground level, where the LES predictions are known to be a challenging task.  相似文献   

Comparative energetics of ERA-40, JRA-25 and NCEP-R2 reanalysis, in the wave number domain   总被引：1，自引：0，他引：1  

C.A.F. Marques  A. Rocha  J. Corte-Real   《Dynamics of Atmospheres and Oceans》2010,50(3):375-399

The European Centre for Medium-Range Weather Forecasts 40-year Reanalysis (ERA-40), the Japan Meteorological Agency and Central Research Institute of Electric Power Industry 25-year Reanalysis (JRA-25), and the National Centers for Environmental Prediction and Department of Energy AMIP-II Reanalysis (NCEP-R2) are intercompared through a global energetics analysis for all seasons.Overall, the Lorenz energy cycle is consistent among the three datasets. The flow of energy and the peaks and slopes in the spectra of the various components agree between the three reanalysis. Additionally, the temporal variability of the energy cycle terms shows consistency between the three reanalysis. Most differences between the three reanalysis are related to the magnitudes of energy forms and energy conversion/transfer rates at each wave number, generally following the relation ERA−40>JRA−25>NCEP−R2, and mainly located in the Southern Hemisphere. The best agreement between the three datasets is found for northern winter. Differences between the three datasets are greater for the other seasons, being greatest for northern summer. In general, these discrepancies are fairly modest, being likely due to the different model biases and resolutions, and the different data assimilation methods used by the respective reanalysis systems. The energetics of the three reanalysis become closer to each other in more recent years, which is likely due to the increase in the number of observations assimilated in the reanalysis.The NCEP-R2 reanalysis spectrum is smoother than those of ERA-40 and JRA-25, likely due to filtering and to its lower resolution model. The spectra show a rapid decrease for short waves in NCEP-R2 (n=36) and ERA-40 (n=63), as a consequence of filtering. The energy source in the nonlinear wave–wave interactions of kinetic energy, L(n), has a narrower spectral range in NCEP-R2 than in the other datasets. Energetics from the newer JRA-25 reanalysis is generally closer to that of ERA-40, with some exceptions as is the case of zonal–wave interactions of kinetic energy, M(n), for synoptic waves, or for eddy available potential energy, A_E, in the lower troposphere, for which JRA-25 is closer to NCEP-R2.  相似文献   

Evaluating cost-effective strategies for meeting regional CO₂ targets     

JC Bollen  AMC Toet  HJM de Vries 《Global Environmental Change》1996,6(4):359-373

Various climate protocol proposals oblige different industrialized countries to reduce CO₂ and other greenhouse gas emissions. In principle, the total costs of these obligations could be substantially reduced if emission reductions are implemented in regions with low marginal costs for CO₂ reduction. This has been difficult to quantify because of lack of models with suitable regional and sectoral detail. In this paper we perform these calculations by taking advantage of the capability of the IMAGE 2 model to compute regional emissions and costs. Two main options are examined for allocating emission reductions required of industrialized regions in a cost effective manner: (1) allocating them among industrialized regions (2) allocating them among all world regions. The cost savings for each of these options are presented. The main conclusions are that (a) it is of great importance for the cost comparisons of protocols to use a well defined baseline scenario and clearly formulated targets, and (b) large economic benefits, in the order of 35–65%, can accrue from joint-implementation agreements which allocate investments on the basis of net marginal costs of CO₂ emission reduction.  相似文献   

Some new radio sources associated with the sersic peculiar galaxies     

Pierre Kaufmann  P. Marques Dos Santos  M. Alcina Bráz  R. M. Borges 《Astrophysics and Space Science》1975,32(2):L25-L27

  相似文献