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682.More information
This article is a synthesis of the first observations of use of the Internet in French firms. The authors review knowledge of Internet-related processes which are now sufficiently advanced and generalized to allow for an objective view, yet new and unstable enough to justify interest in this period as a stage in trajectories in-the-making. About twenty corporate cases are studied. The article successively presents modes of deployment of intranet and new information and communication technologies, the main uses and functions opted for, and effects on the organization, especially on the development of occupations and skills. Two main conclusions are drawn. There is wide diversity in deployment strategies and modes of appropriation, both between firms and within the same firm. NIC technologies are therefore not the instrument of a new integrated organization; instead, they structure segmented sub-units which have established specific modes of cooperation.
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683.More information
AbstractMany studies have shown a link between intensive agricultural practices and groundwater pollution by nitrates. In Québec, recent studies have shown that the Yamaska River is highly contaminated by agricultural activities. Maize and pork production are particularly intensive in the Noire River sub-basin. In this area, quaternary deposits are discontinuous, of limited thickness and are generally permeable, leading to high groundwater vulnerability. The objective of this study was to determine groundwater vulnerability to nitrate contamination on a small agricultural sub-watershed of the Noire River. The methodology included aquifer characterization, analysis of nitrate concentrations and δ18O composition, as well as a vulnerability evaluation and groundwater flow modelling.Located on the south shore of the Saint Lawrence River, the Noire River (1579 km2) is located in the southeastern portion of the Yamaska basin. A small part of the basin (100 km2) was the focus of this study. The Noire River flows in the centre of the study area whereas the Aulnages creek is a small tributary to the Noire River. The study area was limited to the east and west by topographic highs. It is located between the limit of the St. Lawrence Lowlands and the first Appalachian ridges. The bedrock, Cambrian to Ordovician in age, is mainly made of limestone in the western zone and is composed of terrigenous siliciclastic facies in the eastern zone. The substratum forms elongated crests, due to the tectonic grain, surrounded by recent surface deposits. These quaternary deposits are discontinuous and are of limited thickness. The hydrological potential of the fractured rock aquifer is interesting but spatially variable.The deposits were analyzed at 50 observation sites and 18 typical samples were sieved or submitted for density analysis (GEOTERAP). Data from the Système d'Information Hydrogéologique (SIH) were used to complete the field information in establishing the stratigraphy of the area. Soil hydraulic conductivity was measured using a Guelph permeameter and two short-term pumping tests were performed. Monthly water levels were measured in 18 private wells from June 2001 to June 2002. Water was sampled bimonthly from 35 sites (25 deep wells, two shallow wells, two sites in the Noire River, four in the Aulnages stream, and two in a temporary lake, located in a gravel pit). In October 2001 and April 2002, water was sampled for δ18O composition. Analyses were performed at the GÉOTOP-UQÀM-McGill laboratories. Aquifer vulnerability was determined using the AQUIPRO approach, a simple method that considers clay and till thickness, in addition to well depth. A groundwater flow model was developed using MODFLOW and MODPATH to simulate groundwater flow, flow paths and residence times.Characterization of the quaternary deposits confirmed the following sequence, from the base to the top: till; clayey silts; sand and sandy gravel. The thickness of these deposits was variable, and there were bedrock outcrops, mainly on the western and eastern sides of the study area. A north-south esker (partially exploited) is present on the western side of the Noire River. Measured soil hydraulic conductivities show that the clayey silts and till deposits have low permeability whereas the sand is more permeable. Clayey silts present in the centre of the study area, as well as occasional till deposits, offer partial protection to the aquifer, whereas elsewhere infiltration and contaminants can reach the aquifer through recharge. Pumping tests showed high transmissivities for the rock formation, probably resulting from the important rock fracturing in the upper 10 to 15 m of the aquifer. Groundwater flowed towards the river from the eastern and western limits of the study area, and water depth was on average 2.5 m. The Noire River is generally in contact with rock and drains the aquifer.Measured nitrate concentrations exceeded 10 mg N‑NO3/L (guideline for potable water) in the two sampled surface wells. Concentrations were between 1 and 10 mg N-NO3/L at least once during the study period in ten of the 25 deep sampled wells, indicating a groundwater contamination problem of anthropogenic origin. The highest concentrations were measured in recharge areas and nitrate concentrations were found to decrease generally with well depth. Nitrate concentrations were higher in the Aulnages creek than in the Noire River, probably because the creek intercepts drainage water and shallow groundwater flow. The isotopic composition of surface wells, deep wells and Aulnages creek water remained relatively stable between sampling times. This indicates an important mixing of fresh recharge with in situ groundwater. In the Noire River, δ18O compositions reflect the yearly variations in precipitation.AQUIPRO aquifer vulnerability was highest in the eastern and western parts of the study area where the highest nitrate concentrations were measured. AQUIPRO vulnerability was lowest where the clayey silts provide some protection near the Noire River. The results showed an important spatial heterogeneity in the thickness of the clayey silt layer, underlining the generally high aquifer vulnerability in the study region. The groundwater flow model developed using field data simulated the measured heads adequately. Flow directions simulated with MODPATH confirmed the presence of a shallow groundwater flow from the eastern and western limits and towards the Noire River. This flow is probably responsible for the decreasing nitrate concentrations observed with increasing water sampling depth and confirms that aquifer vulnerability varies with depth in the aquifer. The average groundwater residence time is 20 years. This means that recharge will take on average 20 years to travel through the aquifer and to the Noire River. It also indicates the time frame required for the aquifer to eliminate a large-scale nitrate contamination, after the initiation of control measures.This work showed that groundwater nitrate contamination is related to groundwater vulnerability, which is a function of quaternary deposits, substrate stratigraphy and groundwater flow directions. These factors must be considered when studying groundwater vulnerability as they directly affect contaminant transport. It therefore appears necessary to use a combination of various approaches to better understand aquifer vulnerability and to design preventive measures. This work also demonstrated groundwater contamination by nitrates in the study region. Because of the generally high vulnerability of the aquifer, increased nitrate contamination can be expected in the future if no preventive measures are undertaken to protect the groundwater resource.
Keywords: vulnérabilité, eau souterraine, nitrates, contamination, agriculture, AQUIPRO, modélisation hydrogéologique, Québec, vulnerability, groundwater, nitrates, contamination, agriculture, AQUIPRO, groundwater modelling, Province of Quebec
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684.More information
In agricultural regions, groundwater contamination by nitrogen compounds originating from fertilizers is one of the most significant environmental problems. Along with in situ monitoring, simulation models have been developed for non point pollution (nitrates, pesticides) in order to evaluate both the level and the extent of the contamination. Simulation models, originally intended for research purposes in relation to the dynamics of agricultural systems, have been adapted and applied to environmental management in order to quantify water volumes and contaminant masses likely to reach groundwater systems. Recently, mechanistic models such as Agriflux (Banton et al., 1993) have been developed for use in the field. Agriflux is based on a mechanistic approach to the processes and incorporates a stochastic analysis that takes into account the spatial variability of the parameters. lt. calculates nitrate concentrations as well as water fluxes in the unsaturated zone. In the present study, environmental management principles integrating heterogeneity in soils and agricultural practices were applied to an agricultural watershed in Poitou (France). Preliminary simulations were carried out in order to estimate the influence of various parameters on the nitrate and water fluxes. First, a three-year wheat mono-crop was simulated using the same fertilization rate for each year. The calculated nitrate concentrations follow a trend opposite to that of the seasonal growing crop. To estimate the influence of the soil characteristics on the nitrate concentrations, the four types of soil in the watershed were simulated using the same three-year crop rotation. The results show that the soil type directly influences the amount of nitrate leaching. Under different soils types, the evolution of the concentrations over time follows the same pattern, but the concentration levels are significantly different. To quantify the impact of crops on the nitrate concentrations, the main crop rotations were simulated for the same type of soil. This set of simulations underlines the environmental differences between winter and spring crops. lt. also shows the differences induced by the presence of residues. The La Jannerie watershed was divided into homogeneous zones for soil and crop characteristics. During a four-year period, seasonal and annual nitrate concentrations were calculated for each homogeneous zone from the daily water and nitrate fluxes simulated with Agriflux. The results demonstrate the influence of the agricultural practices on the calculated concentrations. Overall, nitrate levels remain quasi-constant during the periods when the crops are active but vary considerably during the winter when the crops are absent or inactive. This winter period corresponds to a peak in nitrate leaching because of the excess rainfall and the absence of nitrogen uptake by the plants. The incorporation of crop residues in the soil in the autumn generates a high production of nitrates during winter due to the mineralization of the organic nitrogen.Two different environmental approaches can be used jointly to evaluate agricultural practices. The first consists of a comparison between the nitrate flux that can reach the saturated area and the fertilizer rate. This approach provides an estimate of the amount of nitrogen lost to the aquifer. Simulations with Agriflux show that the nitrate fluxes are highest during the autumn when plant uptake is non-existent, except in fields with winter crops. The second approach compares the calculated nitrate concentrations that may occur in the aquifer with recognized water quality criteria. lt. is interesting and important to note that, during the simulated period, the calculated concentrations in the leach were often much lower than the water quality criterion (50 mg NO3/L). This result indicates that the fertilization practices applied in the watershed during this period tended to approach the real crop requirements (minimal requirements) and were more environmentally adequate (environmental optimum) than those used previously.
Keywords: Pollution diffuse, nitrate, gestion environnementale, zone non saturée, modélisation, bassin versant, Agriflux, Non point source contamination, NPS, nitrate, environmental management, unsaturated zone, simulation, watershed, Agriflux
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685.More information
Certain towns and cities frequently suffer from failures of their sewer networks, especially in rainy weather. Pollution of the host environment, as the direct consequence of occasionally untimely spills, is not appreciated by the natural environment or the human population. Improving the quality of the natural environment therefore involves an increasingly sophisticated control of the hydraulics and the pollutant load in drainage systems, and especially in sewer networks. Real-time management of sewer networks can provide a solution for the protection of the natural environment. In this case, control strategies are provided for the sluices and pumps of the sewer network during a rainy event to minimize the urban effluent. Moreover, a better understanding and modeling of the transport of pollution in the mains is required.To that end, not only must the hydraulic operation of the mains be correctly modeled (shape of the hydrograph, value and temporal position of the peak flow), but this numerical model must also be stable and converge towards the solution, irrespective of the initial conditions for modeling of the pollution, and the computer time must be compatible with the requirements of real-time management. The most representative model of unidimensional flows is that of Barré de Saint-Venant (1871). The non-linearity of the model, resulting in difficulties in solving these equations, together with the computer time required, are such that not all the criteria for a real-time application can be met. The conceptual equations model of Muskingum is another model that can be used.In the case of round sewerage mains with a slope ranging from practically nil to a few per-thousandths and a few kilometers long, the K and α coefficients traditionally used do not yield correct results with respect to the benchmark model of Barré de Saint-Venant. To keep the advantages of the simplification of the Muskingum equations, and to avoid having to solve the Barré de Saint Venant system, we propose new parameters for the Muskingum equations and we use optimization and correlation calculation techniques using neural networks.In modeling the mains of a sewer network, the discretization of their length, within the usual limits [50 m; 1000 m] is chosen empirically. This discretization plays an essential part in the propagation of the wave in a main. To take this effect into account, the round main of length L is discretized into N sections, and K is expressed on the basis of the maximum speed of the flow Vmax. The model setting parameters are now N and α, and will be calibrated for a wide range of slopes, lengths and flow rates for round mains with a constant roughness.The calculation procedure is as follows: - Setting of the optimal values of N and alpha giving results close to those calculated by Barré de Saint Venant; - Determination of correlations of the parameters N and alpha according to the slope, length and diameter; - Validation of the Muskingum model in relation to that of Barré de Saint-Venant. The parameters alpha and N are set by minimizing an objective function giving the agreement between the results of the hydraulic simulations by Barré de Saint-Venant and the simulations of the proposed model. The objective function is defined by the sum of the relative quadratic deviations of the values and times of maximum flow rates. The maximum errors are in fact reduced from 90% to 10% on peak flows and from 30% to 10% at a given point in time during the peak flow. The mean error is reduced forty-fold for peak flow, and five-fold in the temporal position, with a reduction of the same order for the standard deviations. Correlations of alpha and N are sought according to the slope, length and diameter of the mains modeled. As linear type relations failed to provide satisfactory results, the multi-layer Perceptron type (artificial) neural network model was used. The model includes 3 inputs and 2 outputs. The first, essential stage consists of finding the optimal number of neurons in the masked layer. It is important to mention that despite maximum errors of 40% and 20% on the prediction of time and peak flow rate, mean errors of only 3% and 4% are observed. Given this result, 4 neurons were chosen in the masked layer. This model therefore includes 3 inputs, 4 neurons in the masked layer, and 2 outputs. Following the learning phase with the results of the optimization phase, the so-called prediction phase was then performed. This consists of using the neural network with data with intermediary values with respect to those used in the learning phase. The neural network is used solely to predict values within the minimum and maximum limits of the learning phase. The prediction (or validation) phase revealed that the mean errors are in the order of 2.7% for the peak flow value and 5.5% for the instant of the same flow. The choice of 4 neurons in the masked layer during the prediction phase gives results with the same order of magnitude as in the learning phase, thus validating the structure of the neural network chosen. Subsequently, the proximity of the value and of the time position of the maximum flow rate for the propagation of rectangular hydrograms was studied. The performance of the model proposed is now verified by studying the propagation of a hydrogram of any given shape. Use of this model, validated on a hydrogram of any given shape and presenting several peaks of different intensities, yields a satisfactory reproduction of the output hydrogram and is a distinct improvement on the classic Muskingum model.
Keywords: Equations de Muskingum, optimisation non linéaire, réseau de neurones, écoulement à surface libre, réseau d'assainissement, Muskingum model, non-linear optimization, neural networks, open channel flow, sewer network
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686.More information
Offshoring of services is an increasingly frequent practice among firms. The employment of foreign workers directly leads to cultural diversification of human resources within the business's value chain. An overview of 76 papers published between 1996 and 2009 in 26 international management journals reveals that culture is exclusively presented as a threat, despite the existence of a literature clearing pointing out the benefits of diversity. Here we propose paths for future research aimed at developing of more nuanced perspective about cultural diversity in an offshoring context.
Keywords: Délocalisation, culture, diversité, différences culturelles, Offshoring, culture, diversity, cultural differences, Deslocalización, cultura, diversidad, diferencias culturales
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688.More information
The research, writing, and publication of the first biography of the English composer, pianist, and critic Kaikhosru Shapurji Sorabji (1892–1988), published in 2013 on the Sorabji Resource Website, managed by its author, is a major project that took place over many years. This article consists of a guided visit to the biographer's workshop, in order to shed light on the challenges, research techniques, difficulties encountered, and the solutions that were entailed in this project conceived to provide the reader with the ideal basis for future research.
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689.More information
This article consists of a reflection on the nature of technique in the writings of Marx. First, the manner in which Marx raises the question of technique from his ontology of the auto-production of species being will be presented. From there on the Marxist critique of the machine is analyzed according to its ontology of auto-production. The analysis of the machine proposed by Marx in chapter XIII of Capital allows a critical return to the now famous passage from the Grundrisse, commonly designated as a “fragment on machines” and mobilized by numerous contemporary post-capitalist theorists such as the cognitivists and accelerationists. Against their productivist vision, the aim will be to advance a reading that would allow the overcoming of the aporias resulting from the unilateral analyses of technological development under capitalism, be they progressive or romantic.
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690.More information
Using the context of the numeric transformation of the book as a backdrop, this article explores the challenges associated with the metadata of the book. The situation in France allows us to analyse the availability of metadata by the various stakeholders, commercial or otherwise, and compare their relative value. The development of the numeric book modifies the context and emerging partners are identified: the production of metadata amongst libraries, publishers and intermediaries, but there are a few limitations. The issue of the durability of the offer made by commercial intermediaries is examined as well as the economic future of the metadata of the book, increasingly diversified to meet the requirements of new services.