Quality assessment of single-channel EEG for wearable devices

The recent embedding of electroencephalographic (EEG) electrodes in wearable devices raises the problem of the quality of the data recorded in such uncontrolled environments. These recordings are often obtained with dry single-channel EEG devices, and may be contaminated by many sources of noise which can compromise the detection and characterization of the brain state studied. In this paper, we propose a classification-based approach to effectively quantify artefact contamination in EEG segments, and discriminate muscular artefacts. The performance of our method were assessed on different databases containing either artificially contaminated or real artefacts recorded with different type of sensors, includingwet and dry EEG electrodes. Furthermore, the quality of unlabelled databases was evaluated. For all the studied databases, the proposed method is able to rapidly assess the quality of the EEG signals with an accuracy higher than 90%. The obtained performance suggests that our approach provide an efficient, fast and automated quality assessment of EEG signals from low-cost wearable devices typically composed of a dry single EEG channel

On-road measurements of VOCs and NOx: determination of light-duty vehicles emission factors from tunnel studies in Brussel city center, 5th Sino-French Joint Workshop on Atmospheric Environment

International audienc

Photocatalytic de-pollution in the Leopold II tunnel in Brussels: NOx abatement results

SSCI-VIDE+CARE:+ABO:YDU:CGOInternational audienceDuring the European Life+ project PhotoPAQ (Demonstration of Photocatalytic remediation Processes on Air Quality), photocatalytic remediation of nitrogen oxides (NOx) was studied in the Leopold II tunnel in Brussels, Belgium, using photocatalytic cementitious coating materials and an artificial UV lighting system. Three different approaches were used to quantify the pollution reduction, i.e. measurements before/after application, upwind/downwind of the test section and with UV lamps on/off. In contrast to first estimations based on laboratory studies on fresh samples, the field results showed no observable reduction of NOx in the tunnel. An upper limit of 2% was determined for the maximum possible NOx reduction, which corresponds to the experimental uncertainties. Serious passivation of the surface reactivity under the heavily polluted tunnel conditions by one order of magnitude was identified in laboratory experiments subsequent to the tunnel study as the main reason for the observed low remediation. In addition, high relative humidity and wind speed inside the tunnel further limited the photocatalytic uptake of NOx. When using the uptake kinetics from the laboratory experiments on passivized tunnel samples, simple model calculations based on a first order reaction kinetics indicate only an upper limit photocatalytic remediation inside the 160 m tunnel section of 0.4%, which is clearly below the experimental uncertainties and thus, in excellent agreement with the tunnel results. Optimized experimental conditions, for which this technology might be applicable in road tunnels, are discussed. (C) 2014 Elsevier Ltd. All rights reserved

On-road measurements of VOCs and NOx: determination of light-duty vehicles emission factors from tunnel studies in Brussel city center, 5th Sino-French Joint Workshop on Atmospheric Environment

International audienc

On-road measurements of VOCs and NOx: determination of light-duty vehicles emission factors from tunnel studies in Brussel city center, 5th Sino-French Joint Workshop on Atmospheric Environment

International audienc

Photocatalytic abatement results from a model street canyon

SSCI-VIDE+CARE+RCI:FBE:ABO:NCA:YDU:CGOInternational audienceDuring the European Life+ project PhotoPAQ (Demonstration of Photocatalytic remediation Processes on Air Quality), photocatalytic remediation of nitrogen oxides (NOx), ozone (O3), volatile organic compounds (VOCs), and airborne particles on photocatalytic cementitious coating materials was studied in an artificial street canyon setup by comparing with a colocated nonactive reference canyon of the same dimension (5 × 5 × 53 m). Although the photocatalytic material showed reasonably high activity in laboratory studies, no significant reduction of NOx, O3, and VOCs and no impact on particle mass, size distribution, and chemical composition were observed in the field campaign. When comparing nighttime and daytime correlation plots of the two canyons, an average upper limit NOx remediation of ≤2 % was derived. This result is consistent only with three recent field studies on photocatalytic NOx remediation in the urban atmosphere, whereas much higher reductions were obtained in most other field investigations. Reasons for the controversial results are discussed, and a more consistent picture of the quantitative remediation is obtained after extrapolation of the results from the various field campaigns to realistic main urban street canyon conditions

On-road measurements of NMVOCs and NOX: Determination of light-duty vehicles emission factors from tunnel studies in Brussels city center

SSCI-VIDE+CARE+ABO:YDU:CGOInternational audienceEmission factors (EFs) of pollutants emitted by light-duty vehicles (LDV) were investigated in the Leopold II tunnel in Brussels city center (Belgium), in September 2011 and in January 2013, respectively. Two sampling sites were housing the instruments for the measurements of a large range of air pollutants, including non-methane volatile organic compounds (NMVOCs), nitrogen oxides (NOx) and carbon dioxide (CO2). The NMVOCs and NOx traffic EFs for LDV were determined from their correlation with CO2 using a single point analysis method.The emission factor of NOx is (544 ± 199) mg vehicle−1 km−1; NMVOCs emission factors vary from (0.26 ± 0.09) mg vehicle−1 km−1 for cis-but-2-ene to (8.11 ± 2.71) mg vehicle−1 km−1 for toluene. Good agreement is observed between the EFs determined in the Leopold II tunnel and the most recent EFs determined in another European roadway tunnel in 2004, with only a slight decrease of the EFs during the last decade. An historical perspective is provided and the observed trend in the NMVOCs emission factors reflect changes in the car fleet composition, the fuels and/or the engine technology that have occurred within the last three decades in Europe

Construction of a photocatalytic de-polluting field site in the Leopold II tunnel in Brussels

SSCI-VIDE+CARE+ABO:CGOInternational audienceWithin the framework of the European Life-F-funded project PhotoPAQ (Demonstration of Photocatalytic remediation Processes on Air Quality), which was aimed at demonstrating the effectiveness of photocatalytic coating materials on a realistic scale, a photocatalytic de-polluting field site was set up in the Leopold II tunnel in Brussels, Belgium. For that purpose, photocatalytic cementitious materials were applied on the side walls and ceiling of selected test sections inside a one-way tunnel tube. This article presents the configuration of the test sections used and the preparation and implementation of the measuring campaigns inside the Leopold II tunnel. While emphasizing on how to implement measuring campaigns under such conditions, difficulties encountered during these extensive field campaigns are presented and discussed. This included the severe de-activation observed for the investigated material under the polluted tunnel conditions, which was revealed by additional laboratory experiments on photocatalytic samples that were exposed to tunnel air. Finally, recommendations for future applications of photocatalytic building materials inside tunnels are given. (C) 2015 Elsevier Ltd. All rights reserved