Méthodologie de validation des données hydrométriques en temps réel dans un réseau d'assainissement urbain

L'objectif du présent travail est l'élaboration d'une méthodologie de validation des données hydrométriques mesurées dans un réseau d'assainissement. L'information validée est utilisée aussi bien en temps réel, pour optimiser les consignes de gestion, qu'en temps différé, pour poser le véritable diagnostic et évaluer, sur une base quotidienne, l'efficacité des systèmes d'assainissement.Le principe de base de la méthodologie proposée repose sur la redondance analytique de l'information provenant d'une part de la mesure directe du débit sur le terrain et d'autre part du débit simulé à partir des variables météorologiques. On compare ainsi d'une part, l'écart entre la valeur prévue par un modèle autorégressif (AR) et la valeur mesurée et d'autre part, l'écart entre la valeur prévue par ce même modèle AR et la valeur simulée par un modèle hydrologique. Parmi les valeurs, mesurée et simulée, celle qui se rapproche le plus de la valeur prévue est retenue. Afin de considérer des modèles non stationnaires et d'éviter le biais d'estimation des paramètres de régression par la méthode standard des moindres carrés, le filtre de Kalman est utilisé pour identifier les paramètres du modèle AR.La méthodologie proposée a été testée avec succès sur un bassin urbain de la municipalité de Verdun. L'hydrogramme mesuré a été bruité artificiellement à la fois par un bruit blanc et par un certain nombre de perturbations de grandes amplitudes et de différentes formes. Le processus de validation a permis de retrouver pratiquement les mesures initiales, non bruitées. Les critères de performance introduits sont largement concluants.We developed an automated methodology for real-time validation of hydrometric data in a sewer network. Our methodology uses real-time validated data to optimise system management and non-real-time data to evaluate day-to-day performance.Two approaches can be used to validate and correct hydrometric data; the choice depends on the number of level gauges present in a system. In single gauge systems, univariate filtering is used to smooth data. For example, frequency filtering systematically eliminates values corresponding to frequencies higher than a predetermined threshold frequency. In systems with several gauging stations-duplex, triplex, or multiplex systems-the multivariate filtering method proposed here can be used to validate data series from each gauge. Material redundancy in duplex or higher order systems makes it possible to detect a deficient gauge, using a decision rule to set aside erroneous readings before averaging accepted values. Part of the underlying principle of this methodology is heavier reliance on gauges that give readings consistent with previous and subsequent validated values in a given series. Thus isolated positive or negative variations within a series are eliminated if corresponding variation values at other gauges are more consistent. To evaluate persistence, a reading is compared to a value predicted by an autoregressive (AR) model calibrated by the previous validated reading.This filtering technique constitutes an intelligent alternative to the frequency filtering method mentioned above. In more practical terms, it compares the deviation of an AR model prediction from a measured value with the deviation of the same AR model prediction from a value estimated by a regressive model at other stations in the network. Among the values measured and estimated by the regressive model, the one nearest the AR model prediction is retained.Our methodology also relies on analytical redundancy generated by direct measurement of flow and hydrological simulation. More precisely, the deviation of the AR model prediction from the measured value is compared with the deviation of the same AR model prediction from a value obtained from a hydrological simulation model. Among measured and simulated values, the one nearest the AR model prediction is retained. To allow consideration of nonstationary models and to avoid the well-known bias of the least squares method, the Kalman filter is used to identify the parameters of the AR model.The methodology we propose employs three models. The first generates analytical redundancy using hydrological modelling. An autoregressive model is then used to predict future runoff rate values. Finally, a voting process model is used to compare measured and simulated values.The proposed methodology was tested on the Verdun sewer system in Quebec with successful results. Two types of artificial disturbance of the measured hydrograph were created: white noise was added to measured values and disturbances of large amplitude and various forms were introduced. The methodology produced the initial values and performance criteria were conclusive. Thus on-site testing confirms that this approach allows completely automated detection and correction of most anomalies. Flood peaks were neither underestimated nor overestimated, and total runoff volumes were retained

N-H...π(pyrrole) Intermolecular Interactions in 1,4-Bis(di-2-pyrrolylmethyl)benzene

The title compound, C₂₄H₂₂N₄, lies about an inversion centre which is at the centre of the 1,4-disubstituted benzene ring. Intermolecular N--H..-Tπ(pyrrole) interactions form a two-dimensional hydrogen-bonded network with shortest N..2(pyrrole centroid) distances of 3.219 (3) and 3.324 (3) A

V-Shape Liquid Crystal-Based Retromodulator Air to Ground Optical Communications

This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties

Analyse de la croissance de Gymnogongrus patens Agardh de la côte atlantique marocaine

La croissance du carraghénophyte, Gymnogongrus patens J. Agardh (Rhodophyta, Phyllophoraceae) a été analysée sur des échantillons d’algues récoltés mensuellement pendant un cycle annuel, d’avril 2002 à mars 2003, sur la plage de Méhdia (Nord ouest de la côte atlantique marocaine). L’analyse des paramètres de croissance (longueur, poids et nombre total de ramifications) de l’algue a montré que sa croissance est plus liée à la prolifération des ramifications qu’à l’élongation des thalles.L’influence des facteurs environnementaux (température, salinité, nitrates, et phosphates) sur l’évolution de la croissance a été étudiée par des analyses en composantes principales (ACP). L’analyse quantitative en composantes principales a montré une variation saisonnière des trois paramètres de croissance. Ainsi, les variables poids, ramifications totales,température, salinité et concentration en nitrates sont corrélées positivement avec l’axe factoriel F1. L‘axe factoriel F2 est corrélé positivement aux variables longueur du thalle et concentration en phosphates. Il est à noter que les teneurs en phosphates sont corrélées négativement avec l’axe F1.Mots-clés : Gymnogongrus patens, croissance, analyses statistiques, Maroc

Asymmetric switching and charge transport in AFLC devices with dissimilar alignment layers

Surface stabilized antiferroelectric liquid crystal (AFLC) devices with dissimilar alignment layers on the two surfaces are characterized by a shift in the electro-optical response [1] so that it is symmetric with respect to a nonzero voltage (figure 1). Because of this shift, the switching state of a pixel which is initially set by applying a short, selection, voltage pulse, may be maintained without applying any holding, bias, voltage. The stability at zero volts, together with the inherent range of grey levels, typical for antiferroelectric liquid crystals, has some potentially very interesting applications. Generally, the magnitude of the voltage shift changes slowly over time, depending on the driving conditions and the materials used. This varying asymmetry is an important obstacle for the implementation of this technology in real devices. Fig. 1. Asymmetric transmission–voltage characteristic of an AFLC cell with dissimilar alignment layers. 2. The influence of charge in asymmetric AFLC devices Charges in AFLCs can considerably influence the switching behavior of the device [2][3]. Measurements of the electric current flowing towards the electrodes of the device when a voltage step is applied can elucidate the nature and the behavior of these charge

The reflective learning continuum: reflecting on reflection

The importance of reflection to marketing educators is increasingly recognized. However, there is a lack of empirical research which considers reflection within the context of both the marketing and general business education literature. This paper describes the use of an instrument which can be used to measure four identified levels of a reflection hierarchy: habitual action, understanding, reflection and intensive reflection and two conditions for reflection: instructor to student interaction and student to student interaction. Further we demonstrate the importance of reflective learning in predicting graduates’ perception of program quality. Although the focus was on assessment of MBA level curricula, the findings have great importance to marketing education and educators

Expression of Protease-Activated Receptor 1 and 2 and Anti-Tubulogenic Activity of Protease-Activated Receptor 1 in Human Endothelial Colony-Forming Cells

Endothelial colony-forming cells (ECFCs) are obtained from the culture of human peripheral blood mononuclear cell (hPBMNC) fractions and are characterised by high proliferative and pro-vasculogenic potential, which makes them of great interest for cell therapy. Here, we describe the detection of protease-activated receptor (PAR) 1 and 2 amongst the surface proteins expressed in ECFCs. Both receptors are functionally coupled to extracellular signal-regulated kinase (ERK) 1 and 2, which become activated and phosphorylated in response to selective PAR1- or PAR2-activating peptides. Specific stimulation of PAR1, but not PAR2, significantly inhibits capillary-like tube formation by ECFCs in vitro, suggesting that tubulogenesis is negatively regulated by proteases able to stimulate PAR1 (e.g. thrombin). The activation of ERKs is not involved in the regulation of tubulogenesis in vitro, as suggested by use of the MEK inhibitor PD98059 and by the fact that PAR2 stimulation activates ERKs without affecting capillary tube formation. Both qPCR and immunoblotting showed a significant downregulation of vascular endothelial growth factor 2 (VEGFR2) in response to PAR1 stimulation. Moreover, the addition of VEGF (50–100 ng/ml) but not basic Fibroblast Growth Factor (FGF) (25–100 ng/ml) rescued tube formation by ECFCs treated with PAR1-activating peptide. Therefore, we propose that reduction of VEGF responsiveness resulting from down-regulation of VEGFR2 is underlying the anti-tubulogenic effect of PAR1 activation. Although the role of PAR2 remains elusive, this study sheds new light on the regulation of the vasculogenic activity of ECFCs and suggests a potential link between adult vasculogenesis and the coagulation cascade

Electrooptic characterization of tunable cylindrical liquid crystal lenses

In this work, one-dimensional arrays of cylindrical adaptive liquid crystal lenses were manufactured and characterized; and test devices were filled with nematic liquid crystal. Comb interdigitated electrodes were designed as a mask pattern for the control electrode on the top glass substrates. A radial graded refractive index along each microsized lens was achieved by fabricating a layer of high resistance sheet deposited as a control electrode. These tunable lenses were switched by applying amplitude and frequency optimized waveforms on the control electrode. Phase profiles generated by the radial electric field distribution on each lens were measured by a convectional interferometric technique