Sedimentary and hydraulic characterization of a heterogeneous glaciofluvial deposit: Application to the modeling of unsaturated flow

International audienceFlows in the unsaturated zones of alluvial deposits are often poorly understood at the scale of structures such as stormwater infiltration basins. The heterogeneous nature of the sediment inherent to this type of formation can lead to preferential flows. The difficulty of quantifying them lies in obtaining hydrodynamic parameters representative of the soil structure in-situ, when the latter is inaccessible. This study proposes a method of estimating the hydrodynamic parameters of the lithofacies composing a glaciofluvial deposit (east Lyon, France) and their integration in a 2D flow model to model flow in the unsaturated zone. The approach developed comprises a sedimentological study based on the Miall code, carried out to determine the analogy between the lithofacies of the study site and those of two glaciofluvial reference sites currently in the process of formation (Chamonix, France; Breidamerkurjökull, Iceland), thereby permitting easy access to all the lithofacies identified on the study site. The water retention and hydraulic conductivity curves were obtained on the reference sites by using Beerkan type infiltration tests for finely textured materials, completed by the Arya and Paris model and data from the literature for coarser materials. Thus hydrofacies corresponding to all the lithofacies were charac- terized. These hydrofacies were used to model a drainage phase on the study site at the scale of a trench (13.50 m long × 2.50 m deep). The model highlighted the importance of the role played by the spatial distribution of hydrofacies on flows, with a pronounced capillary barrier effect of the very coarse lithofacies and a sand lens leading to funneled flows. By assuming that there is a direct link between the sedimentary lithological heterogeneity and the unsaturated hydrodynamic properties of the materials composing its different structures, it was possible to perform a detailed hydrodynamic characterization of the unsaturated zone that could then be used to model flows, and in particular highlight preferential flows

De l'utilisation de méthodes géophysiques pour caractériser les hétérogénéités de dépôts quaternaires alluvionnaires. Intérêt pour l'infiltration des eaux pluviales

Colloque avec actes et comité de lecture. International.International audienceStormwater infiltration basins are generally built on geological formations with large values of hydraulic conductivity. Such is the case for quaternary alluvial formations, among which are glaciofluvial deposits. Two geophysical investigation methods, namely ground-penetrating radar and electrical tomography, were tested on an infiltration basin built on a glaciofluvial deposit. Geophysical profiles were calibrated on a trench wall dug in the glaciofluvial formation. A sedimentological study coupled to geophysical measurements behind the trench wall highlights the three-dimensional architecture of the deposit (paleochannels and high energy deposit). A typology of geophysical facies connected to the sedimentary characteristics was thus established. A simple estimation model of saturated hydraulic conductivities was used to quantify the hydraulic properties of glaciofluvial lithofacies. This study shows that sedimentary heterogeneities generate a strong hydraulic heterogeneity, potentially leading to preferential flows. The orientation of paleochannels is a privileged flow direction. Heterogeneity at the scale of lithofacies must be taken into account in the numerical models of water flow underlying stormwater infiltration basins. A preliminary geophysical investigation, coupled to a localized knowledge of alluvial stratigraphy, can be used to define a realistic hydrostratigraphic model

The Cross-Cultural Knowledge Sharing Challenge: An Investigation of the Co-location Strategy in Software Development Offshoring

Part 4: Software DevelopmentInternational audienceCross-cultural offshoring in software development challenges effective knowledge sharing. While research has suggested temporarily co-locating participants to address this challenge, few studies are available on what knowledge sharing practices emerge over time when co-locating cross-cultural software developers. This paper presents a longitudinal case study of an offshoring project with co-location of Indian and Danish software developers for 10½ months. A community-of-practice (CoP) analysis is offered of what knowledge sharing practices emerge over time and how these where facilitated. The study supports previous studies’ suggestion of co-location in offshoring for helping cross-cultural knowledge sharing. However, the short initial period of co-location suggested in these studies, was insufficient for achieving knowledge sharing practices indicating a CoP. In conjunction with a longer period of co-location four facilitators of cross-cultural knowledge sharing were shared office, shared responsibility for tasks and problems, shared prioritization of team spirit, and a champion of social integration

Stock Market Reaction to Unexpected Growth in Marketing Expenditure: Negative for Sales Force, Contingent on Spending Level for Advertising

Because firms do not publicly report marketing expenditures, most studies of the link between firm value and marketing consider advertising (which is publicly reported for many firms) a proxy for marketing. The authors extend those studies in two ways. First, they broaden the proxy for marketing by considering both advertising and sales force. Second, they offer an explanation for the fact that some studies linking advertising to firm value find a positive relationship, whereas others find a negative relationship. The accounting literature suggests that the link to firm value for both unexpected growth in sales force expenditures and unexpected growth in advertising expenditures should be negative. The authors confirm the hypothesized accounting relationship for sales force expenditures but find a contingent relationship for advertising expenditures. Firm value and unexpected growth in advertising expenditures are negatively related for firms that advertise below the advertising response threshold, but they are positively related for firms that advertise above that threshold. Perhaps because this contingent relationship is difficult for analysts to learn through observation of the stock market, analysts ignore value-relevant advertising expenditure information when they forecast firm valueclos

The Effect of Isopropyl Alcohol and Non-Ionic Surfactant Mixtures on the Wetting of Porous Coated Paper

The influence of isopropyl alcohol and non-ionic surfactant solutions on aqueous droplet wetting behaviour on porous coated paper was determined. Paper coatings provide a micro- and nano-porous surface structure, which strictly speaking cannot be described in simple roughness terms as sub-surface lateral absorption directly impacts on the apparent contact angle. It is this very deviation from an idealised system that leads to novel wetting phenomena. Isopropyl alcohol and surfactant-based systems, both of which are commonly used in the printing industry, show differences in wetting behaviour, on both short and long timescales, with changes in the relative composition of the mixtures. Small variations of 0.1 wt% in surfactant concentration have a dramatic influence on the dynamic surface tension, and thus the wetting. It was observed that the wetting kinetics for isopropyl alcohol and surfactant solutions were different in terms of both wetting area and the penetration rate, even in cases where the dynamic surface tension of the solutions was kept the same. Different stages in the wetting and following drying processes could be observed with near infrared spectral imaging. In addition, the surfactant chemistries such as their degrees of hydrophilicity and molecular weights generated comparative differences in the wetting kinetics. The dominating factor affecting the wetting was, as expected, the solid–liquid interfacial energy defined on the practical porous substrate, which differed from the direct comparison with dynamic surface tension, thus exemplifying the deviation from idealised surface roughness behaviour when considering porous materials. An apparent “equivalent” surface roughness value for the porous material was determined, and it was seen that an increase in this equivalent parameter enhanced the rate of wetting behaviour with decreasing solution surface tension, and so also affected the wetting evolution. The wetting was enhanced by cavities in the coating layer, which were enlarged by the penetrating liquids