Optimal Maintenance Policy for Second-Hand Equipments under Uncertainty

This chapter addresses a maintenance optimization problem for re-manufactured equipments that will be reintroduced into the market as second-hand equipments. The main difference of this work and the previous literature on the maintenance optimization of second-hand equipments is the influence of the uncertainties due to the indirect obsolescence concept. The uncertainty is herein about the spare parts availability to perform some maintenance actions on equipment due to technology vanishing. The maintenance policy involves in fact a minimal repair at failure and a preventive repair after some operating period. To deal with this shortcoming, the life cycle of technology or spare parts availability is defined and modeled as a random variable whose lifetimes distribution is well known and Weibull distributed. Accordingly, an optimal maintenance policy is discussed and derived for such equipment in order to overcome the uncertainty on reparation action. Moreover, experiments are then conducted and different life cycle of technologies are evaluated according to their obsolescence processes (accidental or progressive vanishing) on the optimal operating condition

Effects of Nitrogen Fertilization on Mycorrhizal Infection, Nodulation and Growth of Phaseolus vulgaris L.

The common bean (Phaseolus vulgaris L.) has been the subject of a number of studies and has been described by many authors as a legume with low nitrogen fixing potential compared to other legume species. The first objective of this study is to assess the development and growth of P. vulgaris L. var. Djedida and its yield at different developmental stages (vegetative, flowering and fruiting), in the presence and absence of nitrogen fertilizer (Urea 46) in an arid climate and in a soil containing high level of CaCO3 and assimilable phosphorus. The second objective is to carry out a survey on nodulation, number of spores and mycorrhizal infection under these conditions. The results showed that the nitrogen fertilizer amendment is mainly significant (p< 0.0001) for various morphological parameters. Indeed, great improvement was observed on the majority of the morphological parameters with considerable percentages. However, no significant effect was reported for the roots length. In addition, a negligible number of nodules were obtained in the plot without fertilization and no significant effect on the number of spores was recorded. Furthermore, the effect of fertilization on the arbuscular intensity (a%, A%) and on mycorrhizal colonization (M%, m%) of the roots was found to be significant. The soil in the arid region of Biskra showed significant mycorrhizogenic potential, although the conditions in this region were not very favorable for their development, which could constitute an effective biological resource to improve the tolerance of host plants to biotic and abiotic constraints

Free Energy of Adsorption of Methylene Blue on Polyvinyl Chloride Containing Iron Oxide Nanoparticles Coated with Poly[2-(dimethylamino)ethyl methacrylate]

International audienceThe free energy of adsorption is a parameter that describes the affinity between adsorbent and adsorbate; this affinity has a close relationship with the nature of the chemical or physical forces which can be formed, at the adsorbent-adsorbate interface. In the present work a polyvinyl chloride (PVC) based nanocomposite film containing poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) coated-iron oxide nanoparticles (IONPs) was prepared; this material was then used for methylene blue (MB) removal from water. The IONPs were synthesized by a co-precipitation method, coated with PDMAEMA using the emulsion approach, and then dispersed in a film of PVC. Ultraviolet-visible (UV-Vis) spectroscopy was used to study the MB adsorption process on the prepared nanocomposite; the obtained results showed that the adsorption process of MB onto the PVC-based nanocomposite film was linear as a function of initial MB concentrations in the range from 10(-7) to 10(-4 )mol/L; the free energy of adsorption was calculated using the Langmuir isotherm and found to be -46.82 kJ/mol with a high adsorption equilibrium constant of 2.93 x 10(6) L/mol, indicating that the mechanism of the MB adsorption process was chemisorption. The synthesized PDMAEMA, coated IONPs, and uncoated IONPs were thoroughly characterized by Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance Spectroscopy (H-1 NMR), and Scanning Electron Microscopy (SEM)