This research work deals with the problem of karst sinkhole collapse occurringin the last few years in Cheria area. This newly revealed phenomenon is of amajor constrain in land use planning and urbanization, it has become necessarytoassess the stability of these underground features before any planningoperation. Laboratory testing and field work were undertaken in order todetermine both intact rock and rock mass properties. All the rock mechanicstesting and measurement were undertaken according to the ISRMrecommendations.It has been found that under imposed loading, the stability of the karst cavitiesdepends on the geo-mechanical parameters (Rock Masse Rating; RMR,Geological Strength Index; GSI, and Young Modulus; E) of the host rock aswell as the depth and dimensions of the gallery. It increases with RMR, GSI, Eand depth and decreases as the cavity becomes wider. Furthermore, thecalculation results show that a ratio (roof thickness to gallery width) of 0.3 andmore indicate, a stable conditions.The results obtained in this work allow identifying and assessing the stability ofunderground karst cavities. The methodology followed in this paper can betaken as a road map in the establishment of a hazard map related to the studiedphenomenon. This map will be a useful tool for the future urban extensionplanning in Cherea area.

This article proposed a new smart diagnosis algorithm of the open-circuit fault in a PV generator. For the faults conventional diagnosis, it used the analysis of the actual operation parameters of the PV generator. For the faults smart diagnosis, it based on the optimization of SVM technique by the neural network for the classification of observations located on its margin. The resulting algorithm can ensure a better monitoring function of the open-circuit fault within the PV generator, with a high classification rate and a low error rate.

The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons.

Three steroidal glycosides were isolated from the bark of Dracaena fragrans (L.) Ker Gawl. "Yellow Coast", and a fourth from the roots and the leaves. Their structures were characterized on the basis of extensive 1D and 2D NMR experiments and mass spectrometry, and by comparison with NMR data of the literature. These saponins have the spirostane-type skeleton and are reported in this species for the first time.