Distributed Recognition of Reference Nodes for Wireless Sensor Network Localization

All known localization techniques for wireless sensor and ad-hoc networks require certain set of reference nodes being used for position estimation. The anchor-free techniques in contrast to anchor-based do not require reference nodes called anchors to be placed in the network area before localization operation itself, but they can establish own reference coordinate system to be used for the relative position estimation. We observed that contemporary anchor-free localization algorithms achieve a low localization error, but dissipate significant energy reserves during the recognition of reference nodes used for the position estimation. Therefore, we have proposed the optimized anchor-free localization algorithm referred to as BRL (Boundary Recognition aided Localization), which achieves a low localization error and mainly reduces the communication cost of the reference nodes recognition phase. The proposed BRL algorithm was investigated throughout the extensive simulations on the database of networks with the different number of nodes and densities and was compared in terms of communication cost and localization error with the known related algorithms such as AFL and CRP. Through the extensive simulations we have observed network conditions where novel BRL algorithm excels in comparison with the state of art

Ammonia emissions from a soil amended with urea and inhibitor of urease activity in a Mediterranean area

Urea and ammonium-based fertilisers are nowadays one of the most important sources of ammonia (NH3) emissions to the atmosphere in Europe. However, little is known about NH3 volatilisation in Mediterranean areas. The aim of the present study was the quantification of NH3 emissions by using the Integrated Horizontal Flux (IHF) method after application of urea with the urease inhibitor N-(n-butyl) thiophosphorie triamide (NBPT) to a semiarid agricultural soil. The field experiment was carried out at "La Poveda" field station in Madrid on a sunflower crop in spring 2006. Urea and a mixture of urea and the inhibitor (0.14%) were surfaee-applied by hand at a rate of 170 kg N ha"' to eircular plots (diam. 40 m). The soil was irrigated with 10 mm of water just after the applieation of urea to dissolve and incorporate it onto the first layer of soil. There were three peaks in the NH3 flux over the duration of the measurement period (36 d). The first peak was associated to irrigation and the others to rainfall events. The total NH3 emission during the whole experiment (36 days) was 17.3 ±5.5kgNH3-N ha"1 in the ease of urea treated soils and 10.0 ± 4.5 kg NHrN ha"' where NBPT was ineluded with the urea

Type en toedieningsvorm van N-kunstmest: effecten op gewas- en eiwitproductie en -kwaliteit

Dit rapport probeert een antwoord te geven op de vraag hoe melkveehouders de beperkte hoeveelheid stikstof(N)meststoffen maximaal kunnen benutten naast de op het bedrijf aanwezige dierlijke mest. Daartoe is in opdracht van Productschap Zuivel een literatuurstudie uitgevoerd naar de effecten van het gebruikte type en de toedieningsvorm van N-kunstmeststoffen op de gewasopbrengst, de N-opname en eiwitkwaliteit. Nagegaan is of de N-benutting verhoogd kan worden door een betere inzet van meststoffen en beperking van de verliezen door ammoniakvervluchtiging, nitraatuitspoeling, denitrificatie en lachgasontwikkeling. Naast type en toedieningsvorm zijn ook fysiologische en fysische aspecten van de meststoffen in de afweging meegenomen. Veredeling en een betere voorspelling van de N-mineralisatie uit de bodem kunnen een rol spelen om de N-benutting te verhogen. Verder zijn de bodemkwaliteit, de voorziening met overige nutriënten en het management belangrijke aspecten om de N-benutting te verbeteren. In een Handreiking zijn tenslotte de verschillende aspecten samengebracht in een advies voor de praktijk

Inovações tecnológicas no manejo do nitrogênio para o arroz irrigado.

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