26,410 research outputs found

    The European Market for Organic Products: Growth and Development

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    The European Market for organic food has been growing rapidly in terms of both supply and demand during the 1990s. However, national markets develop in many different directions. In some countries the market share ist quiet high while in others a market for organic farming products nearly does not exist. This book detects and compares the national markets of the main organic products in 18 European countries - the 15 EU countries plus Switzerland, Norway and the Czech Republic - on the basis of the most comprehensive collection of data ever presented covering the period 1993 - 1997/1998. It is shown that European demand is far from being satisfied and the major efforts in organising a transparent international market and developing marketing strategies is necessary to realise this potential. This book is aimed at policy makers, the private sector, researchers and students in the field of economics and politics of organic farming

    Advanced passive communication satellite systems comparison studies. Volume 1 - Summary Final report

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    Passive communication satellites feasibility for Comsat system - Vol.

    Lateral vibration effects in atomic-scale friction

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    The influence of lateral vibrations on the stick-slip motion of a nanotip elastically pulled on a flat crystal surface is studied by atomic force microscopy (AFM) measurements on a NaCl(001) surface in ultra-high vacuum. The slippage of the nanotip across the crystal lattice is anticipated at increasing driving amplitude, similarly to what is observed in presence of normal vibrations. This lowers the average friction force, as explained by the Prandtl-Tomlinson model with lateral vibrations superimposed at finite temperature. Nevertheless, the peak values of the lateral force, and the total energy losses, are expected to increase with the excitation amplitude, which may limit the practical relevance of this effect.Comment: To appear in Applied Physics Letter

    Quantitative flaw characterization with scanning laser acoustic microscopy

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    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. In accuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw

    Abrasion of flat rotating shapes

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    We report on the erosion of flat linoleum "pebbles" under steady rotation in a slurry of abrasive grit. To quantify shape as a function of time, we develop a general method in which the pebble is photographed from multiple angles with respect to the grid of pixels in a digital camera. This reduces digitization noise, and allows the local curvature of the contour to be computed with a controllable degree of uncertainty. Several shape descriptors are then employed to follow the evolution of different initial shapes toward a circle, where abrasion halts. The results are in good quantitative agreement with a simple model, where we propose that points along the contour move radially inward in proportion to the product of the radius and the derivative of radius with respect to angle
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