Ajustements nationaux de mécanismes prix face aux fluctuations du prix mondial: les leçons du coton en Afrique Zone Franc
The French colonial power committed itself in promoting cotton, well before its colonization was achieved. Promotion eventually succeeded only from 1952 onward, thanks to the set up of a pricing mechanism which integrated the needed adaptation to world price fluctuations. Since 1985, this mechanism was adjusted several times, along the collapses of the world price which came out more frequently with great magnitude. The adjustments did not lead to the expected results, although production kept on increasing, because the cotton sectors were close to bankruptcy several times. In most African francophone countries, the very conflicting relationship between stakeholders resulted directly or indirectly from the mechanism adjustments. This article analyses the errors and difficulties in adjusting pricing mechanism under the pressure, still very vivid, of world price fluctuations.
Organisation locale d'adaptation au marché mondial du coton : le cas du Mali
Apres la grave crise du marche cotonnier (1984-85), deux agro-economistes ont analyse la situation dans un pays producteur et envisage des solutions de type financier face a de futurs aleas. L'efficacite d'une forme d'organisation locale pour adapter le secteur productif aux fluctuations des cours mondiaux du coton est montree. Il s'agit d'une "auto-subvention" des intrants par les paysans producteurs eux-memes. L'etude montre que ce systeme est plus efficace que la distribution actuelle de "ristourne" au cas ou le cours mondial est eleve
A new method of near field analysis
The problem of the accurate determination of the total electromagnetic field produced by a current distribution on a circular disc type aperture is examined. For comparison of the near and Fresnel region solutions, an exact Maxwellian integral is used as the starting point. Aperture and space coordinates are separated by the use of Bessel function addition theorems, allowing the field to be expressed as a sum of terms containing radial and angular integrals. The radial integrals involve only the disc (aperture) distribution and coordinates while the angular integrals involve only the elevation angle. The distance from origin appears implicitly in the series coefficients. These integrals are suitable for high speed computations and have been evaluated for a number of cases. The results are compared with the small angle and general Fresnel formula values for various observation angles, distances from the aperture, and aperture distributions.