Plant voedt bodem: Uit onderzoek blijkt dat planten belangrijker zijn voor het voeden van de bodem dan bemesting.

In de biologische landbouw wordt vaak gezegd dat je eerst de bodem moet voeden en dat zo vanzelf de plant wordt gevoed. Uit onderzoek komt echter steeds duidelijker naar voor dat de plant zelf een zeer belangrijke rol speelt bij het voeden van de bodem. Daarmee is de cyclus gewas>beworteling>bodemleven>bodem>gewas weer rond

Model Equation for the Dynamics of Wrinkled Shockwaves: Comparison with DNS and Experiments

International audienceA model equation for the dynamics and the geometry of the wrinkled front of shock waves, obtained for strong shocks in the Newtonian limit, is tested by comparison with direct numerical simulations and a shock tube experiment

Acoustical Excitation for Damping Estimation in Rotating Machinery

In experimental modal analysis a structure is excited with a force in order to estimate the frequency response function. Typically, this force is generated by a shaker or a hammer impact. Both methods have proven their usefulness, but have some well-known disadvantages. A main disadvantage of the shaker is that it has to be fixed to the structure whereas with a hammer it is not possible to excite a specific frequency. To overcome these disadvantages, alternative non-contact methods can be used. There are several non-contact techniques, i.e. pressurized air, laser, acoustics, etc. By using acoustics as an excitation technique it is easy to select an excitation signal going from random noise to a simple sine. Also the equipment to produce the acoustic excitation is rather cheap. However, the state of the art does not offer a straightforward technique to estimate the excitation force, making it difficult for applications such as experimental modal analysis. In this research, acoustic excitation is compared with hammer excitation to estimate the frequency response function of two shafts. Especially a method to validate the force induced by the acoustics is derived. The final purpose of this research is to estimate the damping properties of rotating machinery

Tese: "Os audioguias na acessibilidade aos museus. A sua aplicação ao Museu da Ciência da Universidade de Coimbra"

Os audioguias na acessibilidade aos museus. A sua aplicação ao Museu da Ciência da Universidade de Coimbra Autora: Maria João Martins Pereira Neto Orientação: Pedro Júlio Enrech Casaleiro e Irene Maria de Montezuma de Carvalho Mendes Vaquinhas Dissertação apresentada no âmbito do 2º Ciclo em História, Especialização em Museologia, da Faculdade de Letras da Universidade de Coimbra. Júri: João Paulo Cabral de Almeida Avelãs Nunes (que presidiu); Pedro Júlio Enrech Casaleiro (orientador); Irene ..

MESURE DES PROBABILITES DE TRANSITION DES RAIES 51D2, 61D2, 71D2 → 51P1 DU CADMIUM

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p-type doping by platinum diffusion in low phosphorus doped silicon

In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8–32 hours in 0.6, 30, and 60 Ω cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ω cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation