254 research outputs found

    Humidity-insensitive water evaporation from molecular complex fluids

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    We investigated theoretically water evaporation from concentrated supramolecular mixtures, such as solutions of polymers or amphiphilic molecules, using numerical resolutions of a one dimensional model based on mass transport equations. Solvent evaporation leads to the formation of a concentrated solute layer at the drying interface, which slows down evaporation in a long-time scale regime. In this regime, often referred to as the falling rate period, evaporation is dominated by diffusive mass transport within the solution, as already known. However, we demonstrate that, in this regime, the rate of evaporation does not also depend on the ambient humidity for many molecular complex fluids. Using analytical solutions in some limiting cases, we first demonstrate that a sharp decrease of the water chemical activity at high solute concentration, leads to evaporation rates which depend weakly on the humidity, as the solute concentration at the drying interface slightly depends on the humidity. However, we also show that a strong decrease of the mutual diffusion coefficient of the solution enhances considerably this effect, leading to nearly independent evaporation rates over a wide range of humidity. The decrease of the mutual diffusion coefficient indeed induces strong concentration gradients at the drying interface, which shield the concentration profiles from humidity variations, except in a very thin region close to the drying interface.Comment: 13 pages, 10 figure

    Empty Container Management in the Benelux Waterways

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    The scientific contribution of this paper is the development of a model for empty container management in the hinterlands of the ports of Antwerp and Rotterdam. The objective of the proposed model is to minimize the total operational cost while satisfying the demand for empty containers. This goal is achieved by choosing the most efficient transportation mode between a seaport and its hinterland: road, inland waterways or intermodal transport. Moreover, to fit the real-life operation and management as well as possible, our model also includes container substitution and container leasing options.Peer reviewe

    Нестаціонарний колокаційно-ітеративний метод розв’язування крайової задачі для звичайних диференціальних рівнянь з параметрами

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    Розглядається питання застосування нестаціонарного колокаційно-ітеративного методу до розв’язування крайових задач для звичайних диференціальних рівнянь з параметрами. Побудовано алгоритм методу, встановлено достатні умови його збіжності.The question of non stationary collocation-iterative method appliance concerning the The question of non stationary collocation-iterative method appliance concerning the boundary problem solution for the simple differential equations with parameters is substantiated. The methods algorithm is built, and sufficient conditions for convergence are found here
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