Real- and synthetic-array signal processing of buried targets     

Pinto  M.A. Bellettini  A. Hollett  R. Tesei  A. 《Oceanic Engineering, IEEE Journal of》2002,27(3):484-494

Results from two field experiments aimed at investigating the detection and classification of buried targets are presented. In both experiments a 2-16-kHz parametric source was used. In the first experiment, the source was used in combination with a 12-m horizontal line array and in the second with a 1.4-m vertical line array which was displaced horizontally along an underwater rail to form a 10 m /spl times/ 1.4 m two-dimensional synthetic aperture sonar (SAS). To increase the SAS integration time, the parametric source was electronically scanned in azimuth during the displacement along the rail, as in spotlight mode. It is shown that both arrays allow important signal-to-reverberation gains, enhancing the detection of sub-bottom echoes. A new, environmentally adaptive, matched filter which further improves the signal to reverberation ratio while allowing discrimination between proud and buried targets is presented and validated experimentally. The use of resonant scattering for target classification of buried objects is discussed, in the particular case of spherical shells.  相似文献   

Radioactivity backgrounds in ZEPLIN-III     

H.M. Araújo  D.Yu. AkimovE.J. Barnes  V.A. BelovA. Bewick  A.A. BurenkovV. Chepel  A. CurrieL. DeViveiros  B. EdwardsC. Ghag  A. HollingsworthM. Horn  G.E. KalmusA.S. Kobyakin  A.G. KovalenkoV.N. Lebedenko  A. Lindote  M.I. LopesR. Lüscher  P. MajewskiA. St. J. Murphy  F. Neves  S.M. PalingJ. Pinto da Cunha  R. PreeceJ.J. Quenby  L. ReichhartP.R. Scovell  C. SilvaV.N. Solovov  N.J.T. SmithP.F. Smith  V.N. StekhanovT.J. Sumner  C. ThorneR.J. Walker 《Astroparticle Physics》2012,35(8):495-502

We examine electron and nuclear recoil backgrounds from radioactivity in the ZEPLIN-III dark matter experiment at Boulby. The rate of low-energy electron recoils in the liquid xenon WIMP target is 0.75 ± 0.05 events/kg/day/keV, which represents a 20-fold improvement over the rate observed during the first science run. Energy and spatial distributions agree with those predicted by component-level Monte Carlo simulations propagating the effects of the radiological contamination measured for materials employed in the experiment. Neutron elastic scattering is predicted to yield 3.05 ± 0.5 nuclear recoils with energy 5-50 keV per year, which translates to an expectation of 0.4 events in a 1 yr dataset in anti-coincidence with the veto detector for realistic signal acceptance. Less obvious background sources are discussed, especially in the context of future experiments. These include contamination of scintillation pulses with Cherenkov light from Compton electrons and from β activity internal to photomultipliers, which can increase the size and lower the apparent time constant of the scintillation response. Another challenge is posed by multiple-scatter γ-rays with one or more vertices in regions that yield no ionisation. If the discrimination power achieved in the first run can be replicated, ZEPLIN-III should reach a sensitivity of ∼1 × 10⁻⁸pb · yr to the scalar WIMP-nucleon elastic cross-section, as originally conceived.  相似文献   

Geochemical study of submicron particulate matter(PM1)in a metropolitan area     

Ismael L.Schneider  Elba C.Teixeira  Guilherme L.Dotto  Diana Pinto  Cheng-Xue Yang  Luis F.O.Silva 《地学前缘(英文版)》2022,(1):417-429

Air pollution has become a major problem in urban areas due to increasing industrialization and urbanization.In this study ambient concentrations of PM1 and metal concentrations as well as source contributions were identified and quantified by using Positive Matrix Factorization(PMF)in receptor modeling in the Metropolitan Area of Porto Alegre,Brazil.The PM1 samples were collected on PTFE filters from December 2012 to December 2014 in two sampling sites.Major ion and trace element concentrations were assessed.The average concentrations were 12.8 and 15.2μg/m³ for Canoas and Sapucaia do Sul sites,respectively.Major ion contributions of PM1 were secondary pollutants such as sulfate and nitrate.Trace elements,especially Cu,Pb,Zn,Cd,and Ni also made important contributions which are directly associated with anthropogenic contributions.Our results show significantly higher levels in winter than in summer.Most of the PM1 and the analyzed PM species and elements originated from anthropogenic sources,especially road traffic,combustion processes and industrial activities,which are grouped in 7 major contributing sources.A back-trajectory analysis showed that the long-range transport of pollutants was not relevant in relation to the contribution to PM1 and metal concentrations.This work highlights the importance of urban planning to reduce human health exposure to traffic and industrial emissions,combined with awareness-raising actions for citizens concerning the impact of indoor sources.  相似文献   

Climate change scenarios for precipitation extremes in Portugal     

Ana C. Costa  Jo?o A. Santos  Joaquim G. Pinto 《Theoretical and Applied Climatology》2012,108(1-2):217-234

Precipitation indices are commonly used as climate change indicators. Considering four Climate Variability and Predictability-recommended indices, this study assesses possible changes in their spatial patterns over Portugal under future climatic conditions. Precipitation data from the regional climate model Consortium for Small-Scale Modelling–Climate version of the Local Model (CCLM) ensemble simulations with ECHAM5/MPI-OM1 boundary conditions are used for this purpose. For recent–past, medians and probability density functions of the CCLM-based indices are validated against station-based and gridded observational dataset from ENSEMBLES-based (gridded daily precipitation data provided by the European Climate Assessment & Dataset project) indices. It is demonstrated that the model is able to realistically reproduce not only precipitation but also the corresponding extreme indices. Climate change projections for 2071–2100 (A1B and B1 SRES scenarios) reveal significant decreases in total precipitation, particularly in autumn over northwestern and southern Portugal, though changes exhibit distinct local and seasonal patterns and are typically stronger for A1B than for B1. The increase in winter precipitation over northeastern Portugal in A1B is the most important exception to the overall drying trend. Contributions of extreme precipitation events to total precipitation are also expected to increase, mainly in winter and spring over northeastern Portugal. Strong projected increases in the dry spell lengths in autumn and spring are also noteworthy, giving evidence for an extension of the dry season from summer to spring and autumn. Although no coupling analysis is undertaken, these changes are qualitatively related to modifications in the large-scale circulation over the Euro-Atlantic area, more specifically to shifts in the position of the Azores High and associated changes in the large-scale pressure gradient over the area.  相似文献   

Particulate matter geochemistry of a highly industrialized region in the Caribbean:Basis for future toxicological studies     

Luis F.O.Silva  Ismael L.Schneider  Paulo Artaxo  Yuleisy Núñez-Blanco  Diana Pinto  Érico M.M.Flores  Leandro Gómez-Plata  Omar Ramírez  Guilherme L.Dotto 《地学前缘(英文版)》2022,(1):376-387

Air pollution has become an important issue,especially in Caribbean urban areas,and,particulate matter(PM)emitted by different natural and anthropogenic sources causes environmental and health issues.In this work,we studied the concentrations of PM₁₀ and PM_2.5 sources in an industrial and port urban area in the Caribbean region of Colombia.PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000 i-D sampler.Elemental geochemical characterization was performed by X-ray fluorescence(XRF)analysis.Further,ionic species and black carbon(BC)were quantified by ion chromatography and reflectance spectroscopy,respectively.Using the Positive Matrix Factorization(PMF)receptor model,the contributions of PM sources were quantified.The average concentration of PM₁₀ was 46.6±16.2μg/m³,with high concentrations of Cl and Ca.For PM_2.5,the average concentration was 12.0±3.2μg/m³,and the most abundant components were BC,S,and Cl.The receptor model identified five sources for PM₁₀ and PM_2.5.For both fractions,the contributions of marine sea spray,re-suspended soil,and vehicular traffic were observed.In addition,PM_2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions,and secondary aerosol sources with building construction emissions.Further,PM₁₀ was found to also include building construction emissions with re-suspended soil,and metallurgical industry emissions.These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region.  相似文献   

Atacama Field Campaign: laboratory and in-situ measurements for remote sensing applications     

Cristian Mattar  Andrés Santamaría-Artigas  Flavio Ponzoni  Cibele T. Pinto  Carolina Barrientos  Glynn Hulley 《International Journal of Digital Earth》2019,12(1):43-61

This work presents the preliminary results of the first field calibration campaign performed in the Atacama Desert, Chile, between the 18 and 22 August 2014, called the Atacama Field Campaign (ATAFIC 2014). In situ measurements were performed in order to spectrally characterize the surface reflectance spectra between 0.3 and 2.5?µm, radiometric temperature (8.0–14.0?µm) and atmospheric measurements. A soil sample was collected and analyzed using Fourier Transform Infrared Spectroscopy and X-Ray Diffraction techniques to characterize the surface reflectance spectra and mineralogical composition, respectively. ASTER land surface emissivity in addition to GOES, MODIS and Landsat-8 land surface temperature (LST) were also used. Results showed that the spectral features of the Atacama soil and the characteristics of this geographical zone, which is featured as the most hyper-arid and cloudless place in the world, make this area a potential target for surface reflectance characterization. Day and night LST comparison between field and remote sensing data are lower than 2?K and the Root Mean Square Error for land surface emissivity is close to 2%. This work opens the possibilities to consider the Atacama Desert as a reference target for calibration and validation activities for earth observation missions’ purposes.  相似文献   

δ15N and δ13C in the Mondego estuary food web: Seasonal variation in producers and consumers     

Alexandra Baeta  Rute Pinto  Ivan Valiela  Pierre Richard  Nathalie Niquil  João C. Marques 《Marine environmental research》2009,67(3):109-116

Assessments of temporal variation in stable carbon and nitrogen ratios were used to examine seasonal trends of the water column and benthic food webs in the Mondego estuary (Portugal). There was a marked seasonality in weather and water column conditions, including nutrient supply and chlorophyll concentrations. In spite of the pronounced environmental changes, we found little evidence of seasonal variation in δ¹³C and δ¹⁵N of producers and consumers in the Mondego estuary, with a few notable exceptions. Nitrogen isotope ratios in macrophytes (Zostera noltii, Ulva sp., Enteromorpha sp., and Gracilaria sp.), and in two grazers (Idotea chelipes and Lekanesphaera levii) increased during late summer, with the highest δ¹⁵N values being measured in July, during a period of elevated temperatures and drought, which may have favored high rates of denitrification and heavier δ¹⁵N values. The results suggest that stable-isotope values from macrophytes and selected grazers are useful as tracers of seasonal changes in nitrogen inputs into estuaries, and that those of consumers reflect other factors beyond seasonal variations in N and C sources.  相似文献   

Embedded beam element with interaction surface for lateral loading of piles          下载免费PDF全文

Diego F. Turello  Federico Pinto  Pablo J. Snchez 《国际地质力学数值与分析法杂志》2016,40(4):568-582

This paper presents a numerical formulation of a three dimensional embedded beam element for the modeling of piles, which incorporates an explicit interaction surface between soil and pile. The formulation is herein implemented for lateral loading of piles but is able to represent soil–pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The model assumes perfect adherence between beam and soil along the interaction surface. The paper presents a comparison of the results obtained by means of the present formulation and by means of a previously formulated embedded pile element without interaction surface, as well as reference semi‐analytical solutions and a fully 3D finite element (FE) model. It is seen that the proposed embedded element provides a better convergence behavior than a previously formulated embedded element and is able to reproduce key features of a full 3D FE model. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Collaborative fisheries management in the Northeast US: Emerging initiatives and future directions     

Patricia Pinto da Silva  Andrew Kitts 《Marine Policy》2006,30(6):832-841

The nature of participation by fishing organizations in fisheries management in the Northeast US is changing. Evidence of this is the number of groups that are actively seeking opportunities for group governance of marine resources. This article explores emerging collaborative or co-management arrangements in this region (a process whereby decision-making is shared between federal/council level and fishery stakeholder groups) and the shift towards an ecosystem-based approach to the management of marine fisheries.This research suggests that it is an opportune time for the development of a regional policy in the Northeast that provides an enabling environment in support of decentralized governance of federally managed marine fisheries. It also suggests that these initiatives can play a key role in operationalizing ecosystem-based management.  相似文献   

The Soil Geochemical Atlas of Portugal: Overview and applications     

M. Incio  V. Pereira  M. Pinto 《Journal of Geochemical Exploration》2008,98(1-2):22

The continental area of Portugal is now entirely covered by a soil geochemical survey (1 site/135 km²), taking as the sampling media topsoils (upper mineral horizons, A) and organic horizons (humus, O). Standard methods for sampling, sample preparation and analysis were used in order to achieve high quality and consistent data. Each sample was analyzed for 32 chemical elements, pH, electrical conductivity and organic matter content.The main purpose of the survey was to obtain baseline levels for various chemical elements. The compilation of all data (nearly 45,000 individual data) in an organised way, led to the production of the first Soil Geochemical Atlas of Portugal. In this Atlas it is possible to find for each chemical element a set of information statistics (basic statistical parameters, boxplots, cumulative frequency curves, etc.), maps of spatial distribution, among other information of geochemical and environmental interest. This paper gives an overview of the Soil Atlas and examples of application. The data were used to calculate reference values for 9 elements of environmental importance and to obtain empirical formulae allowing the estimation of elements in the coarse fraction of soils (< 2.00 mm) from known concentration in a finer fraction (< 0.18 mm).  相似文献