141 research outputs found

    CFD-based process optimization of a dissolved air flotation system for drinking water production

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    Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions

    Scuttle for shelter: flight-to-safety and political uncertainty during the Spanish Second Republic

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    The Spanish Second Republic was a unique experiment of democratization in interwar Europe, which was characterized by extreme levels of political uncertainty. We find that investors responded to shifts in uncertainty by selling stocks in favor of government bonds—a behavior known as flight-to-safety. Additionally, we find that political uncertainty caused stock market stress and induced significant differences in the cross-section of expected stock returns, consistent with the exposures to political uncertainty. The fact that investors recurrently scuttled to shelter into government bonds suggests that they did not perceive a radical change in the political regime as an immediate and credible threat

    Naar een architectuur van vereenvoudiging? Victor Horta’s lezingen over Amerikaanse architectuur in de jaren twintig

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    The Belgian architect Victor Horta (1861-1947) spent most of the First World War in the United States. Over the course of three years, from December 1915 to January 1919, he explored how the American skyscrapers, standardized dwellings and ingenious urban planning might serve as a model for a modern, post-war Belgium. Yet Horta’s memoirs had very little to say about his discussion of American architecture or any influence his travels might have had on his post-war work. This article consequently breaks new ground in examining the various talks on the subject that Horta gave in the 1920s. Horta’s lectures actually provide a good picture of how he started to see American architecture as a model for the future. In American architectural practice, serial production, standardization and economies of scale facilitated a simplification of the design – a solution Horta also proposed for war-torn Belgium. By way of illustration, the article describes the affinity between Horta’s more classical formal language of the 1920s, as in his 1925 pavilion for the Exposition international des Arts décoratifs et industriels modernes, and the architecture of the United States. It also shows that Horta was an important proponent of American architecture in Belgium, and also played a pioneering role in the introduction of some of its defining features, such as high-rise construction.De Belgische architect Victor Horta (1861-1947) verbleef het grootste deel van de Eerste Wereldoorlog in de Verenigde Staten. Gedurende drie jaar, van december 1915 tot januari 1919, onderzocht hij daar hoe de Amerikaanse wolkenkrabbers, gestandaardiseerde woningen en ingenieuze stedenbouw als model konden dienen voor een modern, naoorlogs België. In zijn memoires was Horta echter erg summier over zijn bespreking van de Amerikaanse architectuur, en de mogelijkse invloed die zijn reis heeft gehad op zijn naoorlogs werk. Dit artikel onderzoekt daarom voor de eerste keer de verschillende lezingen die Horta in de jaren twintig over het onderwerp heeft gegeven. Horta’s voordrachten laten namelijk goed zien hoe hij de Amerikaanse architectuur begon te zien als een model voor de toekomst. Serieproductie, standaardisatie en schaalvergroting werkten in de Amerikaanse architectuurpraktijk een vereenvoudiging van ontwerp in de hand – een oplossing die Horta ook voorstelde in het door de oorlog geruïneerde België. Om dit te illustreren beschrijven de auteurs in dit artikel hoe Horta’s klassiekere vormentaal van de jaren twintig, zoals zichtbaar in zijn paviljoen voor de Exposition internationale des Arts décoratifs et industriels modernes uit 1925, verwant was aan de architectuur in de Verenigde Staten. Het toont daarnaast aan hoe Horta een belangrijke rol heeft gespeeld in het propageren van de Amerikaanse architectuur in België, en ook een pioniersrol heeft gespeeld in de introductie van enkele van haar voornaamste principes, zoals hoogbouw
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