The photovoltaic (PV) generator exhibits a nonlinear current-voltage (I-V) characteristic that its maximum power point (MPP) varies with solar insolation. In this paper, a maximum power point tracking (MPPT) method using fuzzy logic control (FLC) is presented. This method is based on the concept of perturbation and observation (P & O) algorithm to track the MPP of a stand-alone PV system. The controller is used to maximize the power generated by the PV array and the simulation of the system is implemented in MATLAB. Simulation results are compared with those obtained by the conventional P & O controller. Results show that the FLC gives better and more reliable control for the stand-alone PV system feeding hybrid loads.

Objectives: Unraveling mechanisms whereby Pseudomonas aeruginosa becomes resistant to carbapenems through testing 114 non-duplicate P. aeruginosa clinical isolates for their susceptibility to various classes of antibiotics and scrutinizing the production of metallo-β-lactamases (MBLs) by tested isolates. Methods: Susceptibility testing of P. aeruginosa to different antibiotics was determined by Kirby-Bauer disk diffusion method and MBLs production by tested isolates was studied phenotypically and genotypically and PCR products were confirmed by sequencing Results: All tested clinical isolates showed eminent resistance to the majority of tested antibiotics and 14 isolates were imipenem (IPM)-resistant. Furthermore, IPM-resistant isolates were verified to be MBLs-producers. MBLs-encoding genes blaSIM and blaSPM genes were detected by PCR where four isolates were found to harbor blaSPM gene while only one isolate harbored blaSIM gene. The correct size of PCR products of blaSIM and blaSPM genes were sequenced and sequences were submitted to the GenBank databases and assigned the accession numbers KX452682 and KX452683 for blaSIM-2 and blaSPM-1, respectively. Conclusion: Here, we report the emanation of P. aeruginosa clinical isolates harboring blaSPM-1 and blaSIM-2 genes. This may reflect the substantial increase in the rate of imipenem resistance due to MBL in P. aeruginosa clinical isolates from Egypt. Early detection and infection-control practices are of the best antimicrobial strategy for combating this organism.