Randriamalala J.R.,Ecole Superieure des science |
Herve D.,IRD Montpellier |
Randriamboavonjy J.-C.,Ecole Superieure des science |
Carriere S.M.,IRD Montpellier
Agriculture, Ecosystems and Environment | Year: 2012
The objective of this paper is to determine the effects of tillage regime, cropping duration and fallow age on the diversity, structure and floristic composition of secondary vegetation in a tropical forest of eastern Madagascar. Tillage regime was divided into three categories: (1) no tillage, (2) light tillage (local shallow tillage <10. cm deep) and (3) heavy tillage (tillage of the whole plot, 10-20. cm deep). Cropping duration was divided into three classes: (i) short (1-2 years), (ii) medium (3-4 years) and (iii) long (5-15 years). Eighty-nine fallows subdivided in three regrowth age classes (1-5; 6-10 and 11-29 years) were surveyed. We found that heavy tillage regime was associated with a long cropping duration favouring the establishment of herbaceous and wind-dispersed species and reducing species richness, basal area and maximal height. The recovery of species richness and maximum height was faster under no till compared to heavy tillage. Heavy tillage regime favours proliferation of herbaceous species in the middle age regrowths (6-10 years). Long cropping duration (5-15 years) slowed down the recovery rate of maximal height in the old regrowths (11-29 years). A blockage of secondary succession was never found but a total forest recovery takes a longer time when heavy tillage and long cropping duration were observed. © 2012 Elsevier B.V.
Zaibi D.,Ecole Superieure des science |
Riahi M.,Ecole Superieure des science |
Moussa F.,University of Tunis
ACM International Conference Proceeding Series | Year: 2012
With the notion of mobility and computing ubiquity, we have migrated from the user-centered design to the contextbased design, integrating user, platform and environment. We have passed from the presentation ergonomics and adaptation to the user profiles to the contextual ergonomics and the management of nomadic objects. It is against this background that fits our research. We propose, for that purpose, an approach, based on MDA (Model-Driven Architecture) concepts, for ergonomic adaptation to the context. It is based on a generic context model and transformation models. © 2012 ACM ISBN en cours d'attribution.
Battikh T.,Ecole Superieure des science |
Jabri I.,Ecole Superieure des science
Multimedia Tools and Applications | Year: 2011
In this paper, we present a procedure to estimate the position, orientation and focal length of a camera in a soccer field. These parameters are then used in real-time overlay of graphics on a soccer pitch. The method uses court model composed by arcs and lines. A means of automatically initializing the tracking process is also presented which uses Hough transform with a combination of a non-linear least squares optimization method. For the tracking of camera parameters, two cases arise: the center of the pitch and the 18 m area. A combination of automatic court model recognition with the Kanade-Lucas-Tomasi (KLT) algorithm is also used. © 2010 Springer Science+Business Media, LLC.
Mustapha M.B.,Ecole Superieure des science |
Abdeljellil C.,Ecole Superieure des science
Revue des Sciences de l'Eau | Year: 2011
In order to improve the process of water disinfection (waste water and drinking water) by UV-C irradiation, a low pressure UV lamp was supplied by two types of electronic power: traditional power at 50 Hz and high frequency power at 64 KHz. The simulation of bacterial inactivation kinetics using a mathematical model of « series-events » demonstrated the ability of the high frequency UV lamp to provide an effective UV dose capable of inactivating bacteria over a shorter exposure time than that determined for a conventional UV-C lamp. Moreover, the determination of bacterial reactivation factor (Cr) after a rest time in the presence and or in absence of visible light showed an irreversible inactivation in the tested bacteria of the photo-dependent and photo-independent reactivation mechanisms in the case of irradiation by the high frequency UV-C lamp. The increase in the bacterial inactivation without subsequent reactivation, for a reduced time of UV exposure, is consistent with the increase of the monochromatic UV spectral radiant flux at 253,7 nm provided by the high frequency power supply UV-C lamp (64 KHz). The increase of germicidal UV flux overcomes the disadvantages related to the use of a conventional UV lamp, namely the determination of a lethal dose and problems related to bacterial reactivation after treatment by ultraviolet light.