References of "Sensors and actuators. B, Chemical"
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See detailLong term stability of metal oxide-based gas sensors for e-nose environmental applications : an overview
Romain, Anne-Claude ULg; Nicolas, Jacques ULg

in Sensors and actuators. B, Chemical (2010), 146

The e-nose technology has enormous potentialities for in site monitoring of off-odours. However a number of limitations are associated with the properties of chemical sensors, the signal processing ... [more ▼]

The e-nose technology has enormous potentialities for in site monitoring of off-odours. However a number of limitations are associated with the properties of chemical sensors, the signal processing performances and the real operating conditions of the environmental field. The field experience of the research group included testing of a large amount of sensors in different sensor technologies and among those the metal oxide-based gas sensors (Figaro type) are the best gas sensors for long term application, as stated during more than 1 year of field testing. To be usable for the off-odours field measurement, the e-nose has to deal with the lack of long term stability of these sensors. The drift and the sensors replacement have to be considered. In order to appraise the time evolution of the sensors and the effect on the results of an electronic nose, experimentation has been performed during more than 3 years on two identical sensor arrays. The two arrays contain the same six Figaro sensors and are in the same sensor chamber of the e-nose system. Both arrays have worked continuously, without break. This paper presents the drift of some TGS sensors for 7 years as well as the difference in the temporal behaviour of identical sensors and the consequence on the e-nose results after the sensor replacement in the sensors array. A correction of the drift and of the replacement effect is applied and the classification results are exposed, with and without correction. [less ▲]

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See detailComplementary approaches to measure environmental odours emitted by landfill areas
Romain, Anne-Claude ULg; Delva, Julien ULg; Nicolas, Jacques ULg

in Sensors and actuators. B, Chemical (2008), 131(1), 18-23

This paper presents different methods to assess the odour emission and the odour annoyance in the surroundings. It is shown, on the example of landfill areas and composting facilities, that chemical ... [more ▼]

This paper presents different methods to assess the odour emission and the odour annoyance in the surroundings. It is shown, on the example of landfill areas and composting facilities, that chemical analyses are helpful to identify key compounds of the odour release, and to set up the specification of a monitoring instrument. Sensitive methods, like dynamic olfactometry or sniffing team investigation, are mainly applicable to provide a global odour plume or an average annoyance zone. And the electronic nose can supply a warning signal to the plant manager or a real time estimation of the annoyance zone. [less ▲]

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See detailDetection of diverse mould species growing on building materials by gas sensor arrays and pattern recognition
Kuske, Martyna; Padilla, M.; Romain, Anne-Claude ULg et al

in Sensors and actuators. B, Chemical (2006), 119(1), 33-40

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array. Four moulds species have been considered. Pattern classification provides detection ... [more ▼]

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array. Four moulds species have been considered. Pattern classification provides detection rates on the order of 80-85% for different species. Drift degrades only slightly these values subsequent test 4 months later. [less ▲]

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See detailThe electronic nose as a warning device of the odour emergence in a compost hall
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Ledent, Catherine

in Sensors and actuators. B, Chemical (2006), 116(1-2), 95-99

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as ... [more ▼]

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as discriminant analysis, are able to recognize, in real time, the odour of compost with respect to other possible sources in the hall. The paper shows that with unsupervised methods, such as principal component analysis, it is not essential to identify all the possible odour sources during the learning phase. The closeness to the compost group centroid could be used as an indicator of the compost odour level. Alternatively, by a suitable calibration from olfactory measurements, the signals generated by the sensor array can be used to estimate the odour emission rate from the compost hall. Such real time monitoring should allow to assess and to anticipate the annoyance in the surrounding. [less ▲]

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See detailMonitoring the exhaust air of a compost pile as a process variable with an e-nose
Romain, Anne-Claude ULg; Godefroid, D.; Kuske, M. et al

in Sensors and actuators. B, Chemical (2005), 106(1), 29-35

In this paper, the monitoring of the composting process with an e-nose is presented. An emission chamber is developed for this purpose and put on a household waste compost pile. A lab-made e-nose with ... [more ▼]

In this paper, the monitoring of the composting process with an e-nose is presented. An emission chamber is developed for this purpose and put on a household waste compost pile. A lab-made e-nose with metal oxide sensors is located at the exit of this chamber. Simultaneously to the e-nose measurements, air sampling on sorbent tubes as well as physico-chemical analysis are realised. The adsorbed air samples are analysed in the lab by gas chromatography coupled to mass spectrometry (GC-MS). In addition, some parameters of the composting process are collected (compost temperature, age of the pile, date of the aeration). Correlation between the sensors and 14 chemical families is determined by principal component analysis (PCA). By canonical analysis, two models are developed and calibrated by the proportion of each chemical family and in function of the compost process events. Thanks to these models, monitoring of various kinds of compost process events is possible with only one measurement device. © 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailFuzzy k-NN applied to moulds detection
Kuske, Martyna; Rubio, R.; Romain, Anne-Claude ULg et al

in Sensors and actuators. B, Chemical (2005), 106(1), 52-60

The possibility to detect Aspergillus versicolor growing on different building materials by a metal oxide sensor array is studied. Results show that an accurate classification rate of 89 +/- 3% can be ... [more ▼]

The possibility to detect Aspergillus versicolor growing on different building materials by a metal oxide sensor array is studied. Results show that an accurate classification rate of 89 +/- 3% can be obtained combining an extended linear discriminant analysis plus a fuzzy k-NN classifier. The classification ability of the classifier is assessed within the dataset by crossvalidation and also in a second dataset collected 5 months later. There is a slight decrease in the classification performance for all the algorithms, being the most sensitive the most accurate one. [less ▲]

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See detailEstablishing the limit of detection and the resolution limits of odorous sources in the environment for an array of metal oxide gas sensors
Nicolas, Jacques ULg; Romain, Anne-Claude ULg

in Sensors and actuators. B, Chemical (2004), 99(2-3), 384-392

Odour identification with gas sensor arrays relies on two main parameters: the limit of detection, defined as the concentration of the analyte corresponding to the lowest detectable signal for the sensors ... [more ▼]

Odour identification with gas sensor arrays relies on two main parameters: the limit of detection, defined as the concentration of the analyte corresponding to the lowest detectable signal for the sensors, and the limit of resolution, defined for pair-wise comparisons of vapours, as the concentration levels below which a vapour can no longer be reliably recognised from another one on the basis of its response pattern. For real-life environmental odours, however, it is no longer possible to express such limits in "concentration" terms, because they are complex gas mixtures composed of hundreds of various compounds. The paper tries to assess both limits for odorous sources in the environment firstly by finding an equivalence of the odour concentration, expressed in odorous unit per cubic meter (ou/m3), and the concentration of a reference gas, here the ethanol, and secondly by working with a statistical metric, based on the magnitude and standard deviations along linear projections of clustered response data. The methodology is illustrated for a metal oxide gas sensor array and the odour generated by urban waste composting facilities, which is compared to the background air and to ethanol vapour. [less ▲]

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See detailThree years experiment with the same tin oxide sensor arrays for the identification of malodorous sources in the environment
Romain, Anne-Claude ULg; Nicolas, Jacques ULg; Andre, Philippe ULg

in Sensors and actuators. B, Chemical (2002), (84), 271-277

The paper discusses the ability of recognition models to classify malodours in the environment 3 years after their calibration, with the same sources releasing odours. Two methodologies applicable either ... [more ▼]

The paper discusses the ability of recognition models to classify malodours in the environment 3 years after their calibration, with the same sources releasing odours. Two methodologies applicable either in the lab or in the field are used. The effect of the long term drift of the sensors is highlighted on the results of principal component analysis (PCA) and of discriminant function analysis (DFA). The paper examines also the applicability of some drift counteraction methods proposed in the literature. Handled with some care, a correction based on the drift direction in the principal components subspace should be applicable to the classification of real odorous sources in the field. [less ▲]

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See detailUsing the classification model of an electronic nose to assign unknown malodours to environmental sources and to monitor them continuously
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Wiertz, Véronique et al

in Sensors and actuators. B, Chemical (2000), 69(3), 366-371

The paper provides some considerations resulting from measurements with electronic noses around real sources of malodour in the environment: compost facilities, printing houses, paint shops, waste water ... [more ▼]

The paper provides some considerations resulting from measurements with electronic noses around real sources of malodour in the environment: compost facilities, printing houses, paint shops, waste water treatment plants, rendering plants, settling ponds of sugar factories. The study aims at supplying the concrete information requested by the final user in the field: either a warning signal when the malodour level exceeds some given threshold value, the identification of the source of an odour detected on site, or on-line identification and monitoring of an odour in the field. Very simple instruments are used, either in the laboratory or directly in the field, with a home-made portable e-nose, based on tin oxide sensors. Even with such simple operating conditions, the classification results with DA and PCA are fairly good. The classification functions calibrated with the statistical procedure, on the basis of the learning phase, are used to recognise and to monitor a given malodour. This odour is sometimes mixed with other odorous interferences in the field. The observations reveal some features useful in the frame of the development of a field detector. [less ▲]

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See detailUse of a simple tin oxide sensor array to identify five malodours collected in the field
Romain, Anne-Claude ULg; Nicolas, Jacques ULg; Wiertz, Véronique et al

in Sensors and actuators. B, Chemical (2000), 62(1), 73-79

A laboratory-made malodour sensing system including 12 commercial tin oxide gas sensors (Figaro Engineering) is used to identify five typical sources of olfactive annoyance: printing houses, paint shop in ... [more ▼]

A laboratory-made malodour sensing system including 12 commercial tin oxide gas sensors (Figaro Engineering) is used to identify five typical sources of olfactive annoyance: printing houses, paint shop in a coachbuilding, wastewater treatment plant, urban waste composting facilities and rendering plant. In this work, all the samples are collected in the field from real malodours in uncontrollable conditions. The ability of the system to predict the origin of unknowns odoriferous samples is investigated. The test of various pre-processing data algorithms shows that the best classification results are obtained with a parameter free of the sensor base-line. The differences in sensor responses among the five odours are shown by icon plots and confirmed by principal component analysis, which highlights four representative clusters. Classification models calibrated by discriminant analysis and artificial neural network are validated on unknowns samples. Chemical relationships between the sensors and the classification results proves that the recognition is not fortuitous. In spite of the influence of environmental parameters, results demonstrate the ability of a simple system to detect and identify typical olfactive annoyances. [less ▲]

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