1,720,983 research outputs found
Tau-p mapping based filtering techniques for linear noise attenuation in reflection data
No full textApplication of the cross-hole seismicc tomography to the study of slope stability in a complex rock formation
No full text
Time domain electromagnetic response of a conductive and magnetic permeable sphere via exponential sums
No full textTwo different numerical methods are presented and compared to identify the radius, the magnetic permeability, and the electrical conductivity of a sphere embedded in a uniform time-varying magnetic field, starting from its time-domain electromagnetic response. The first technique, which has been already applied to this problem, is the Prony method whereas the second one, never experimented in this context, is a matrix pencil method. Numerical experiments, which show a better stability of the second approach, are given and future research prospects are presented
A field-scale remediation of residual light non-aqueous phase liquid (LNAPL). Chemical enhancers for pump and treat
Get PDFThe remediation of petroleum-contaminated soil and groundwater is a challenging task. The petroleum hydrocarbons have a long persistence in both the vadose zone and in the aquifer and potentially represent secondary and residual sources of contamination. This is particularly evident in the presence of residual free-phase. Pump-and-treat is the most common hydrocarbon decontamination strategy. Besides, it acts primarily on the water dissolved phase and reduces concentrations of contaminants to an asymptotic trend. This study presents a case of enhanced light non-aqueous phase liquid (LNAPL) remediation monitored using noninvasive techniques. A pilot-scale field experiment was conducted through the injection of reagents into the subsoil to stimulate the desorption and the oxidation of residual hydrocarbons. Geophysical and groundwater monitoring during pilot testing controlled the effectiveness of the intervention, both in terms of product diffusion capacity and in terms of effective reduction of pollutant concentrations. In particular, non-invasive monitoring of the reagent migration and its capability to reach the target areas is a major add-on to the remediation technique. Most of the organic contaminants were decomposed, mobilized, and subsequently removed using physical recovery techniques. A considerable mass of contaminant was recovered resulting in the reduction of concentrations in the intervention areas
A web based integrated solution for groundwater management: applicfation of the datacrossing DSS to coastal aquifer management
No full textEnvironmental sciences are evolving from a simple, local-scale approach toward complex multilayered, spatially explicit regional endeavours. Advances in computer simulation and high performance computing in recent years greatly extends the possibilities in this field, and changes the ways in which land management systems operate. The Datacrossing DSS is a decision support system that relies on a basin-scale groundwater model and a geographically distributed GIS to support decision makers, through a userfriendly web interface, in the field of sustainable water resources management. The portal, for the general user, exposes hydrological applications based on geochemical field data, geophysical surveys, and results of the finite element hydrological CODESA 3-D model quantifying the impact of point/nonpoint pollution. Within an experimental collaborative environment, modules have been developed to run real-time applications based on numerical solvers, run pre-and post-processing codes, and query and map results through the web browser. Our aim is to build a collaborative platform that, by introducing the computational and data-sharing advantages of a GRID infrastructure, promotes joint initiatives and encourages cooperation among interdisciplinary teams operating in the environmental sciences. To illustrate the potential of our decision support system, we present its application to a complex industrial area in Sardinia, Italy (the Portoscuso site) and a less-impacted aquifer in Morocco, province of Tetuan (the Oued aquifer). Copyright © 2008 IAHS Press
FDEM and ERT measurements for archaeological prospections at Nuraghe S'Urachi (West-Central Sardinia)
Get PDFNuraghe S'Urachi is a monumental architectural complex in West Central Sardinia that was probably first built in the Bronze Age and remained occupied continuously into the early Roman Imperial period. It has been the object of systematic and large-scale archaeological investigations in three different phases since 1948 when the first excavations revealed a complex building within a massive defensive wall and multiple towers. Intermittent fieldwork between the 1980s and 2005 subsequently showed that the central nuraghe might comprise up to five principal towers. In 2013, a new collaborative research project, sponsored by Brown University and the Municipality of San Vero Milis, brought together a multidisciplinary research project to investigate this important archaeological site. In this framework, multi-frequency and multi-coil electromagnetic measurements (FDEM) and Electrical resistivity tomography (ERT) were carried out in 2018, 2019, and 2020, over and close to the nuraghe towers, to gain a better understanding of the inner part of the main structure and to investigate the surrounding area that was intensively settled in Phoenician and Punic times. The preliminary results of the geophysical measurements provide new and interesting evidence that supports new hypotheses and suggests possible future archaeological and geophysical strategies to investigate the unexcavated part of the archaeological site of S'Urachi
- …
