Dutch Experience in Irrigation Water Management Modelling

Modeling the soil-water-crop atmosphere system to improve agricultural water management in arid zones (SWATRE); Groundwater approach to drainage design in irrigated agriculture (SGMP); Computer Program for flume and weir design (FLUME 3.0); A hydrodynamic model in the design of operational controllers for water systems (MODIS/MATLAB); Decision support simulation model for water management at a regional and national scale (SIWARE); Management of water delivery systems (RIBASIM/OMIS); A water allocation, scheduling, and monitoring program (WASAM); and Irrigation agencies, farmers and computational decision support tools

Collision warning system based on probability density functions

In this paper, a collision warning method between the host vehicle and target object(s) is studied. A probabilistic collision warning method is proposed, which is, in particular, useful for objects, e.g. vulnerable road users, which trajectories can rapidly change heading and/or velocity with respect to time. A vehicle is equipped with the probabilistic collision warning system and its functionality is validated in experiments with a bicyclist as target object

Simplex solid states of SU(N) quantum antiferromagnets

I define a set of wavefunctions for SU(N) lattice antiferromagnets, analogous to the valence bond solid states of Affleck, Kennedy, Lieb, and Tasaki (AKLT), in which the singlets are extended over N-site simplices. As with the valence bond solids, the new simplex solid (SS) states are extinguished by certain local projection operators, allowing us to construct Hamiltonians with local interactions which render the SS states exact ground states. Using a coherent state representation, we show that the quantum correlations in each SS state are calculable as the finite temperature correlations of an associated classical model, with N-spin interactions, on the same lattice. In three and higher dimensions, the SS states can spontaneously break SU(N) and exhibit N-sublattice long-ranged order, as a function of a discrete parameter which fixes the local representation of SU(N). I analyze this transition using a classical mean field approach. For N>2 the ordered state is selected via an "order by disorder" mechanism. As in the AKLT case, the bulk representations fractionalize at an edge, and the ground state entropy is proportional to the volume of the boundary.Comment: 14 pages, 8 figures, minor typos correcte

Water-promoted ammonia oxidation by a platinum amine complex in zeolite HZSM-5 catalyst

In this study it was found that [Pt(NH3)(4)]HZSM-5 is an active catalyst for the oxidation of ammonia at low temperature that, in contrast with other catalysts, becomes more active in the presence of water. Furthermore, the selectivity to nitrogen was found to increase when water is presen

Mechanics of cooling liquids by forced evaporation in bubbles

Injecting a non-dissolvable gas into a saturated liquid results in sub-cooling of the liquid due to forced evaporation into the bubble. Previous studies assumed the rate of evaporation of liquid into the bubble to be independent of the degree of sub-cooling. In our study we quantify the bubble growth by direct observation using high speed imaging and prove that this hypothesis is not true. A phenomenological model of the bubble growth as a function of the degree of sub-cooling is developed and we find excellent agreement between the measurements and theory. This bubble cooling process is employed in cooling a liquid. By identification of all heat flows, we can well describe the cool down curve using bubble cooling. Bubble cooling provides an alternative cooling method for liquids without the use of complicated cooling techniques

Hergebruik drainwater in stellingenteelt aardbei

Bij de huidige teeltmethode kunnen een groot aantal gewassen niet meer voldoen aan de toekomstige EU richtlijn van 50 ml nitraat per liter in het grondwater. Ook het gewas aardbeien levert problemen op. Door aardbeien op stellingen te telen en het water te hergebruiken ontstaat een gesloten teeltsysteem waarin water en nutriënten optimaal worden gebruikt. Om na te gaan hoe de praktijk tegen deze ontwikkeling aankijkt is een enquête uitgevoerd

Optimal Control for Wind Turbine Wake Mixing on Floating Platforms

Dynamic induction control is a wind farm flow control strategy that utilises wind turbine thrust variations to accelerate breakdown of the aerodynamic wake and improve downstream turbine performance. However, when floating wind turbines are considered, additional dynamics and challenges appear that make optimal control difficult. In this work, we propose an adjoint optimisation framework for non-linear economic model-predictive control, which utilises a novel coupling of an existing aerodynamic wake model to floating platform hydrodynamics. Analysis of the frequency response for the coupled model shows that it is possible to achieve wind turbine thrust variations without inducing large motion of the rotor. Using economic model-predictive control, we find dynamic induction results that lead to an improvement of 7% over static induction control, where the dynamic controller stimulates wake breakdown with only small variations in rotor displacement. This novel model formulation provides a starting point for the adaptation of dynamic wind farm flow control strategies for floating wind turbines.Comment: 6 pages, 8 figures, accepted for publication for IFAC World Congress 202

Beetle eater beheerst de aspergekever bij de oogst van groene asperges in 2010

In Canada is een grote stofzuiger die voor of achter een tractor bevestigd kan worden “Beetle Eater” genaamd, gebruikt ter bestrijding van de coloradokever in aardappelen. Biologische telers hebben zo’n apparaat gekocht om hem in te zetten ter bestrijding van de wortelvlieg in peen. De resultaten vielen tegen en het apparaat is na twee jaar experimenteren niet meer gebruikt. In 2010 is de machine getest in groene asperges tegen de aspergekever op een gangbaar bedrijf in Noord - Brabant. Omdat groene asperges bij gunstige weersomstandigheden dagelijks geoogst worden, is het lastig om tegen dit insect gewasbeschermingsmiddelen in te zetten vanwege de veiligheidstermijn. Door de Beetle eater 1 of 2 keer (direct na elkaar) in te zetten worden de aspergekevers met 50 of 74% gereduceerd. De asperge oogsters merkten meteen wanneer de machine was ingezet omdat het aantal eitjes op de aspergestengels duidelijk afnam. Door de Beetle eater regelmatig in te zetten bleven het aantal afgezette eitjes op de stengels beperkt en zijn het gehele seizoen geen groene asperges bij deze teler afgekeurd en geen asperges daardoor aangemerkt als kwaliteit II. Een aandachtspunt is wel dat na iedere behandeling aspergestengels afbreken. Dit komt enerzijds omdat de rijafstand niet correspondeerde met de zuigmonden van de Beetle eater (scheelde 5 cm) en anderzijds omdat bij oudere percelen de aspergestengels verder uit het hart van de rug kunnen groeien. Door de zuigmond aan te passen (verbreden en iets te vergroten) is de verwachting dat het afbreken van de stengels beperkt wordt