A partial explanation of the dependency of hydraulic conductivity on positive pore water pressure in peat soils
Part of the relationship between positive pore water pressures and hydraulic conductivity in peat soils may be explained by accumulations of methane bubbles. The AA. show how compression and expansion of gas bubbles with changes in pore water
pressure could cause changes in hydraulic conductivity and thus help to explain some observations of dependency of hydraulic conductivity in peats on pore water pressure. Consideration is also given to the effect on hydraulic conductivities of methane gas
Temperature correction of electrical conductivity valves
A method for temperature correction of electrical conductivity data based on regression analysis of the actual temperature/conductivity relationship of a number of water samples from natural streams is presented. The implications are thus especially
Solutions of the heat conduction equation in a non-uniform soil
Une nouvelle méthode d'estimation périodique de la conduction thermique dans un sol non homogène. Il est montré que la vitesse de conduction thermique du sol varie en fonction de la racine carrée de la diffusivité du sol en profondeur
Estimating unsaturated hydraulic conductivity from easily measured soil properties
The authors measured hydraulic conductivity (saturated and unsaturated) on 127 soil cores, which were taken in different horizons of a wide variety of Belgian soil series. The hot air method and the crust method were combined to obtain the complete
range of hydraulic conductivity from saturation to air-dry. Regression equations for estimating the Gardner parameters were established from simple soil properties, such as soil texture, carbon content, bulk density. Three parameters can reasonably well
be estimated from the textural composition and the saturated hydraulic conductivity.
Salt effect on hydraulic conductivity of a vertisol
The changes in saturated hydraulic conductivity, macroscopic swelling and clay dispersivity of a sodic black clay soil in relation to solution concentration and Na adsorption ratio of the percolating solution were measured. Based on the threshold
concentration curves, an empirical relationship relating saturated hydraulic conductivity and soil solution properties has been derived for vertisols and its field applicability established. For all practical purposes, swelling of clay seemed to be the major
factor responsible for loss of saturated hydraulic conductivity of a sodic vertisol.
Winter leaf conductance rates of Pinus strobus L. (eastern white pine)
This study was conducted to measure and examine the winter leaf conductance and transpiration rates among 10 Pinus strobus trees and investigate whether observed leaf conductance and transpiration rates are large enough to merit incorporation
into existing water balance models. The fieldwork was conducted at the Fair Hill Natural Resources Management Area in north-eastern Maryland. The results suggest that winter leaf conductance of and transpiration from P. strobus trees are significant enough
The role of vegetation in baseflow suspended sediment and specific conductance in granite catchments, S. W. England in Channel processes. Water, sediment, catchment controls.
Mesure des concentrations en suspension et de la conductance spécifique du flux de base pendant 14 mois à 30 stations le long de 3,5 km de rivière sur le granite du Dartmoor. Les modifications les plus évidentes sont liées aux changements des
caractéristiques des chenaux et à la concentration sédimentaire en amont. Les changements de conductance spécifique ont été influencés par les apports de marécages. Les barrages de végétation influencent directement la conductance spécifique.
Correlating specific conductivity with total hardness in gypsum karst waters
The aim of this paper is to evaluate how adequately simple specific electrical conductivity measurements in the field may be used to estimate amounts of dissolved gypsum and total disolved solids in gypsum karst areas. To illustrate the foreign ion
Emergence et structuration d'une multinationale européenne du semi-conducteur : le cas de ST Microelectronics
Electronique ; Entreprise multinationale ; Industrie ; Mondialisation ; Politique économique ; Proximité ; Recherche-développement ; Semi-conducteur ; Stratégie territoriale ; Structure de l'entreprise ; Transfert de technologie
L'A. montre l'émergence et la structuration progressive d'une entreprise européenne du semi-conducteur, née en 1987 de la fusion entre une entreprise italienne et une entreprise française. Les deux sociétés ont puisé à l'origine aux Etats-Unis des
ressources technologiques et managériales. La fusion s'inscrit dans une logique d'intégration européenne et a permis une entrée réussie dans le club des dix premiers fabricants mondiaux de semi-conducteurs. Analyse des différentes échelles de fonctionnement
Hydrological model of peat-mound form with vertically varying hydraulic conductivity
The form of raised peat mires can be considered to reflect the form of the saturated water mound. Here, the form of the mire is calculated for non-uniform, depth-dependent hydraulic conductivity of the peat deposit. Although requiring more
The effects of slaking and dispersion on the hydraulic conductivity of clay soils
This paper reports on a method that can be used to measure the hydraulic conductivity (K) of slaked and dispersed soils and to relate K to the degree of dispersion and sodium content of the soil.
Théorie dynamique de la localisation industrielle. Développement et organisation de la production des semi-conducteurs aux Etats-Unis. Le complexe de production de Silicon Valley. Structure spatiale de l'industrie américaine des semi-conducteurs
Discussion: hydrological model of peat-mound form with vertically varying hydraulic conductivity by Adrian C. ARMSTRONG and reply
The AA. argue that the premise on which the peat mound model developed by Armstrong (1995) is based, that hydraulic conductivity shows an exponential decline with depth in bog peats, is unsound. Empirical evidence in the literature
soil conductivity on the temperature at the top of permafrost. Results show that the temperature dependent conductivity function can be used with a temperature based on the surface freezing index to estimate an appropriate single value of the frozen
The one dimensional heat conduction equation is applied to a non-uniform soil in which harmonic boundary conditions are specified. The analytic solutions are derived for practical use and satisfy a law that the thermal diffusivity is proportional
Localisation concentrée de l'industrie des semi-conducteurs est-allemands.
Allemagne ; Allemagne RDA ; Industrie ; Localisation ; Localisation industrielle ; Semi-conducteur ; Système de production ; Technologie
L'A. analyse l'intégration spatiale de l'industrie des semi-conducteurs. La dynamique de la production et de l'innovation est fortement dépendante de la localisation.