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Peer Reviewed
See detailElectrical Resistivity Monitoring of Heat Tracer to Characterize Lab-Scale Hydraulic Conductivity Distributions
Adetokunbo, Peter; Hermans, Thomas ULg; Oware, Erasmus

Poster (2016, December 14)

Knowledge of the spatial variations of hydraulic conductivity (K) is crucial to almost every hydrogeological investigation. The representative scale of K estimates from traditional slug and pumping tests ... [more ▼]

Knowledge of the spatial variations of hydraulic conductivity (K) is crucial to almost every hydrogeological investigation. The representative scale of K estimates from traditional slug and pumping tests are, however, inadequate to accurately predict hydrogeological processes. There is increasing interest in the application of electrical resistivity tomography (ERT) to quantify spatially continuous K variations. ERT estimation of high-resolution K distributions, however, requires continuous injection of saline tracer (ST) into an aquifer over an extended period, which is feasible but impractical. Here, we present electrical resistivity thermography (ERTh) to evaluate the potential application of time-lapse ER monitoring of heat tracer (HT) to characterize high-resolution K architectures. Unlike ST, long term HT experiments are comparatively easier to manage and repeatable with minimal environmental impact. We estimate K variations via petrophysical coupling of flow and heat transport with joint time-lapse ER and discrete multi-level temperature breakthrough curves. We illustrate the strategy with a 2-D lab-scale sandbox experiment. To construct the heterogeneous field, three lenses with high-K properties with each consisting of gravel, coarse sand, and a mixture of coarse and fine sand, were created within a background of comparatively low-K fine sand. The experiment involved continuous injection and extraction of heat, respectively, at the left and right boundaries of the lab-scale aquifer. We simultaneously performed time lapse ER monitoring of the heat transport and temperature measurements at four discrete multi-levels near the heat extraction well. Results of the coupled inversions demonstrate that ER monitoring of heat tracer provides a unique opportunity to characterize high-resolution spatially continuous K variations, which seems more practical for field applications in contrast to that of the traditional ST. [less ▲]

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Peer Reviewed
See detailElectrical resistivity of AnT2Al3 (An = Np, Pu; T = Ni, Pd)
Seret, Alain ULg; Wastin, Franck; Waerenborgh, Joan-Carlos et al

in Physica B: Condensed Matter (1995), 206 & 207

Structural data and resistivity studies of NpNi2Al3, NpxU1−xPd2Al3 (x = 1, 0.5, 0.3, 0.1) and PuPd2Al3 are reported. The resistivity curves display Kondo features and clear anomalies at the magnetic ... [more ▼]

Structural data and resistivity studies of NpNi2Al3, NpxU1−xPd2Al3 (x = 1, 0.5, 0.3, 0.1) and PuPd2Al3 are reported. The resistivity curves display Kondo features and clear anomalies at the magnetic transition. Moreover, at least two kinds of magnetic structure exist in these compounds, one favouring the electrical conductivity and the other decreasing it. [less ▲]

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See detailElectrical resistivity tomography and self-potential case studies for fractured aquifer characterization and monitoring
Robert, Tanguy ULg; Dassargues, Alain ULg; Nguyen, Frédéric ULg

in Geophysical Research Abstracts (2010), 12

Electrical resistivity tomography (ERT) and self-potential (SP) investigations have been conducted in complex carboniferous limestones aquifers in Belgium (synclinorium structures). The aims of this study ... [more ▼]

Electrical resistivity tomography (ERT) and self-potential (SP) investigations have been conducted in complex carboniferous limestones aquifers in Belgium (synclinorium structures). The aims of this study were (1) to detect and characterize fractured zones in hard rock aquifers, (2) to monitor groundwater flow/water content in these fractured or karstic areas and (3) to use geophysical data to support groundwater flow model set-up and calibration. The investigated areas lie in calcareous synclines. Electrical images allowed us to detect and characterize (in terms of direction, width and depth) several less resistive anomalies, which are interpreted in terms of fractured and/or karstic zones. To interpret the ERT images, data errors as well as image appraisal indicators (resolution matrix, sensitivity matrix and DOI index) were analysed and compared. This allowed us to determine the depth of investigation of ERT and to avoid the misinterpretation of the resulting images. Inversions based on focusing scheme are tested against smoothness-constraint inversion on these field data to provide more realistic images on the basis of prior geological knowledge. Self-potential measurements were performed along the electrical profiles and allowed us to find negative anomalies possibly related with groundwater preferential flow pathways. By taking the assumption that only the electrokinetic effect plays a role in the SP signals, we were able to estimate a first distribution of the water table along our profiles. The SP data showed that in this particular tectonic structure, two perpendicular hydraulic gradients are present. The first gradient is related with the main fold axis direction and is the major drainage system. The second hydraulic gradient is related with the flanks of the calcareous valley. Geophysical data concurrently with ‘ground truth’ geological and hydrogeological data allowed us to better understand the groundwater flow in these calcareous synclines and to verify the conceptual groundwater flow model. [less ▲]

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See detailElectrical resistivity tomography and self-potential methods as a tool for fractured aquifer characterization and monitoring
Robert, Tanguy ULg; Nguyen, Frédéric ULg

Poster (2010, January 12)

Electrical resistivity tomography (ERT) and self-potential (SP) investigations are currently conducted in carboniferous limestones in Belgium. The aims of this study are (1) to characterize and (2) to ... [more ▼]

Electrical resistivity tomography (ERT) and self-potential (SP) investigations are currently conducted in carboniferous limestones in Belgium. The aims of this study are (1) to characterize and (2) to monitor the groundwater flow in fractured or karstic area and (3) to use these geophysical data as a help for groundwater flow model conceptualisation and inverse calibration. Large ERT profiles (320 meters) allow us to image the electrical resistivity distribution of the first 60 meters of the subsurface and to detect and characterize (in terms of direction, width and depth) some fractured and/or karstic zones expected to be less resistive. Data errors as well as indicators of resolution (resolution matrix, sensitivity matrix and DOI index) are analysed in order to calculate the depth of investigation of ERT and to avoid the misinterpretation of the resulting images. Self-potential measurements are performed along the electrical profiles and permit us to find some negative anomalies possibly related with groundwater preferential flow pathways. Since SP signals are related with the groundwater flow when taking into account the electrokinetic effect, we are able to estimate a first distribution of the water table along our profiles. These geophysical data concurrently with ‘ground truth’ geological and hydrogeological data give us a way to better understand the groundwater flow in limestone synclines of the Dinant Synclinorium geological structure. Still, further efforts are needed (1) to fully cover the syncline area and (2) to couple the SP, ERT and hydrogeological data through a more complex forward model of the electrokinetic effect of the self-potential method. [less ▲]

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See detailElectrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale
Masy, Thibaut ULg; Caterina, David; Tromme, Oliver et al

in Journal of Contaminant Hydrology (2016), 184

Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of ... [more ▼]

Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clayey loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique. [less ▲]

Detailed reference viewed: 115 (37 ULg)
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See detailElectrical resistivyt tomography as tool to image preferential flow pathways in soils
Kasteel, Roy; Garré, Sarah ULg; Koestel, Johannes et al

Conference (2009)

Detailed reference viewed: 16 (2 ULg)
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See detailElectrical Source Imaging in cortical malformation-related epilepsy : a prospective EEG-SEEG concordance study
RIKIR, Estelle ULg; KOESSLER, Laurent; GAVARET, Martine et al

in Epilepsia (2014), 55(6), 918-932

OBJECTIVE: Delineating the epileptogenic zone (EZ) in refractory epilepsy related to malformations of cortical development (MCD) often requires intracranial EEG recordings, especially in cases of negative ... [more ▼]

OBJECTIVE: Delineating the epileptogenic zone (EZ) in refractory epilepsy related to malformations of cortical development (MCD) often requires intracranial EEG recordings, especially in cases of negative MRI or discordant MRI and video-EEG findings. It is therefore crucial to promote the development of non-invasive methods such as electrical source imaging (ESI). We aimed to (i) analyze the localization concordance of ESI derived from interictal discharges and EZ estimated by stereo-electroencephalography (SEEG), (ii) compare the concordance of ESI, MRI and electro-clinical correlations (ECC) with SEEG-EZ, and (iii) assess ESI added value in the EZ localization. METHODS: We prospectively analyzed 28 consecutive patients undergoing presurgical investigation for MCD-related refractory epilepsy in 2009-2012. ESI derived from 64-channel scalp EEG was interpreted blinded to- and subsequently compared with SEEG estimated ΕZ. Anatomical concordance of ESI with SEEG-ΕZ was compared to that of video-EEG and MRI. We further assessed ESI added value to ECC and MRI. RESULTS: Twelve (43%) patients had temporal and 16 (57%) extratemporal epilepsy. MRI was negative in 11 (39%) and revealed a cortical malformation in 17 (61%). ESI was fully concordant with the EZ in ten (36%) and partly concordant in 15 (53%). ECC presented a full and partial concordance with EZ in 11% and 82% of cases respectively and MRI in 11% and 46% respectively. Of 11 patients with negative MRI, ESI was fully concordant with the EZ in seven (64%), partly concordant in four (36%). ESI correctly confirmed, restricted or added localizations to ECC and MRI in 12 of 28 patients (43%) and in eight of 11 patients (73%) with negative MRI. SIGNIFICANCE: ESI contributes to estimate the EZ in MCD-related epilepsy. The added value of ESI to ECC is particularly high in patients with MCD and negative MRI, who represent the most challenging cases for epilepsy surgery. [less ▲]

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See detailElectrical stimulation as a modality to improve performance of the neuromuscular system
Vanderthommen, Marc ULg; Duchateau, Jacques

in Exercise and Sport Sciences Reviews (2007), 35(4), 180-185

Transcutaneous neuromuscular electrical stimulation (NMES) can modify the order of motor unit recruitment and has a profound influence on the metabolic demand associated with producing a given muscle ... [more ▼]

Transcutaneous neuromuscular electrical stimulation (NMES) can modify the order of motor unit recruitment and has a profound influence on the metabolic demand associated with producing a given muscle force. Because of these differences, interventions that combine NMES with voluntary contractions can provide beneficial outcomes for some individuals. The adaptations evoked by NMES are not confined to the activated muscle but also involve neural adaptations through reflex inputs to the spinal cord and supraspinal centers. [less ▲]

Detailed reference viewed: 104 (7 ULg)
See detailElectrical tomography investigation in bubble columns
Toye, Dominique ULg; Fransolet, Emmanuelle; Léonard, Angélique ULg et al

Scientific conference (2004, August)

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See detailElectrical transport and magnetic properties of Mn3O4-La0.7Ca0.3MnO3 ceramic composites prepared by a one-step spray-drying technique
Vertruyen, Bénédicte ULg; Fagnard, Jean-François ULg; Vanderbemden, Philippe ULg et al

in Journal of the European Ceramic Society (2007), 27(13-15), 3923-3926

La0.7Ca0.3MnO3/Mn3O4 composites can be synthesized in one step by thermal treatment of a spray-dried precursor, instead of mixing pre-synthesized powders. Another advantage of this composite system is ... [more ▼]

La0.7Ca0.3MnO3/Mn3O4 composites can be synthesized in one step by thermal treatment of a spray-dried precursor, instead of mixing pre-synthesized powders. Another advantage of this composite system is that a long sintering step can be used without leading to significant modification of the manganite composition. The percolation threshold is reached at ~ 20 vol% of manganite phase. The 77 K low field magnetoresistance is enhanced to ~ 11 % at 0.15 T when the composition is close to the percolation threshold. (c) 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailElectrical transport and percolation in magnetoresistive manganite/insulating oxide composites: Case of La0.7Ca0.3MnO3/Mn3O4
Vertruyen, Bénédicte ULg; Cloots, Rudi ULg; Ausloos, Marcel ULg et al

in Physical Review. B (2007), 75(16), 165112

We report the results of electrical resistivity measurements carried out on well-sintered La0.7Ca0.3MnO3/Mn3O4 composite samples with almost constant composition of the magnetoresistive manganite phase ... [more ▼]

We report the results of electrical resistivity measurements carried out on well-sintered La0.7Ca0.3MnO3/Mn3O4 composite samples with almost constant composition of the magnetoresistive manganite phase (La0.7Ca0.3MnO3). A percolation threshold (phi c) occurs when the La0.7Ca0.3MnO3 volume fraction is ~ 0.19. The dependence of the electrical resistivity rho as a function of La0.7Ca0.3MnO3 volume fraction fLCMO can be described by percolationlike phenomenological equations. Fitting the conducting regime (fLCMO > phic) by the percolation power law rho # (fLCMO - phic)^(-t) returns a critical exponent value of 2.0±0.2 at room temperature and 2.6±0.2 at 5 K. The increase of t is ascribed to the influence of the grain boundaries on the electrical conduction process at low temperature. (C) 2007 The American Physical Society. [less ▲]

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See detailElectrical transport in saturated and conjugated molecular wires
Remacle, Françoise ULg; Levine, R. D.

in Faraday Discussions (2006), 131

The mechanism for charge transport in dithio molecular wires tethered between two gold electrodes is investigated, using both a steady state and a time-dependent quantum mechanical approach. The interface ... [more ▼]

The mechanism for charge transport in dithio molecular wires tethered between two gold electrodes is investigated, using both a steady state and a time-dependent quantum mechanical approach. The interface with the electrodes is modeled by two gold clusters and the electronic structure of the entire Au-n-S-bridge-S-Au-n system is computed ab initio at the DFT level and semi-empirically, with the extended Huckel theory. Current vs. applied bias, I-V, curves are computed using a scattering Landauer-type formalism in a steady state picture. The applied source-drain and gate voltages are included at the ab initio level in the electronic Hamiltonian and found to influence strongly the I-V characteristics. The time evolution of a non stationary electronic wave packet initially localized on a gold atom at one end of the extended system shows that charge transfer proceeds sequentially, by a hopping mechanism, to the opposite end. Analysis of the effective one electron Hamiltonian matrix shows that the sulfur atom endows a resistive character to the Au-C-S junctions. The S atoms are however rather well coupled to both the gold and carbon atoms so that typically the super exchange limit for electron transfer is not reached unless the molecular bridge is saturated and the Fermi window function is narrow. [less ▲]

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See detailElectrical tuned vibration absorber: application of the equal-peak method to linear and non-linear RL piezoelectric shunts
TONDREAU, Gilles; DERAEMAEKER, Arnaud; Soltani, Payam ULg et al

Scientific conference (2014, October)

Detailed reference viewed: 33 (4 ULg)
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See detailElectrically addressing a molecule-like donor pair in silicon: An atomic scale cyclable full adder logic
YAN, Yonghong; Mol, J. A.; Verduijn, J. et al

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2010), 114

Detailed reference viewed: 47 (0 ULg)
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See detailElectrically charged droplet: Case study of a simple generator
Brandenbourger, Martin ULg; Dorbolo, Stéphane ULg

in Canadian Journal of Physics (2014), 92

Detailed reference viewed: 26 (3 ULg)
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See detailElectricity storage with liquid fuels in a zone powered by 100% variable renewables
Léonard, Grégoire ULg; François-Lavet, Vincent ULg; Ernst, Damien ULg et al

in Proceedings of the 12th International Conference on the European Energy Market - EEM15 (2015)

In this work, an electricity zone with 100% renewables is simulated to determine the optimal sizing of generation and storage capacities in such a zone. Using actual wind output data, the model evaluates ... [more ▼]

In this work, an electricity zone with 100% renewables is simulated to determine the optimal sizing of generation and storage capacities in such a zone. Using actual wind output data, the model evaluates the economic viability of a power-to-fuel storage technology that combines water electrolysis, CO2 capture and methanol synthesis. The main advantage of using methanol as an energy carrier is that liquid fuels are suitable for (long-term) energy storage thanks to their high energy density. The levelized electricity cost projection by 2050 equals 83.4 €/MWh in the base case configuration. The effects of storage round-trip efficiency and the storage unit lifetime are quantified and their impacts on the electricity cost discussed. Additional benefits of using methanol as a fuel substitute may be taken into account in further work. [less ▲]

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See detailElectrification Rurale. Vers une technique innovatrice pour l'Afrique.
Lilien, Jean-Louis ULg; omboua, Alphonse

in Revue d'electricité et d'électronique industrielle (2006), N°1-2006

In many developing countries , there are a lot of high voltage lines which cross many regions to supply electricity to the main towns or connect to networks the distanced electric substations . These ... [more ▼]

In many developing countries , there are a lot of high voltage lines which cross many regions to supply electricity to the main towns or connect to networks the distanced electric substations . These lines, used for supplying electricity to big towns, cross a lot of villages whose people broadly poor hope to be supplied with electricity without a suitable solution. However it seems very deplorable that the power conducted by these lines doesn’t profit to surrounding population. Unfortunately , for these villages , the use of classical substations is too expensive to the power distributors because of high cost of investment and production for these potential scattered consumers with the low demand of electricity. This paper presents the original solution settled in 2002 in one of the village located in Congo Brazzaville and continue to operate correctly in 2006. It is a new power transformer, based on the technique of SF6 measuring transformer, which is connected on one phase of the high voltage line 220kV and which produces the low voltage 230 V directly useful by the rural population. This prototype sample for the rural electrification has been designed to deliver a power of 50kVA. A cheap and robust system ! It requires a large popularization, mainly in sub saharian Africa that has got many such opportunities. Outside the role of bulk power transmission, the high voltage line is now also able to distribute a part of it. [less ▲]

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See detailElectro dynamic fragmentation of printed wiring boards as a preparation tool for their recycling
Martino, Rémi; Iseli, Cedric; Gaydardzhiev, Stoyan ULg et al

in Minerals Engineering (2017), 107

The use of Electro Dynamic Fragmentation (EDF) enables selective fragmentation of materials through generating electrical discharges as a means of fracturing. Liberated materials can be thus processed ... [more ▼]

The use of Electro Dynamic Fragmentation (EDF) enables selective fragmentation of materials through generating electrical discharges as a means of fracturing. Liberated materials can be thus processed downstream in a more efficient way especially when value-added End-of-Life (EoL) electronic equipment is recycled. The aim of this study was to assess the benefits of the EDF technology towards processing of EoL printed wiring boards (PWBs) in view their recyclability. Printed wiring boards were comminuted using EDF at three different settings and with a hammer mill for comparative experiment. The products coming out were characterized by optical microscopy, SEM and liberation oriented leaching. Subsamples from the various EDF stages were inspected to investigate the progress of cracks and degree of copper layers exposure. The different energy levels used during the EDF processing have resulted in different degrees of PWBs damages, starting from components removal to entire structure perturbation and size reduction. EDF has resulted in generation of a lesser amount of fines, however the optimal approach in view energy efficient post-processing of the studied PWBs was the combination between single-stage EDF for components removal only with subsequent shredding of the depopulated boards. [less ▲]

Detailed reference viewed: 32 (5 ULg)