Sharif Digital Repository

Contrary to the widespread understanding, this paper shows by means of mathematics and numerics that a perfect power factor correction cannot be made at the load terminals only. To achieve a perfect power factor correction, the supply commitment is required as well. In the absence of such commitment, the power factor cannot reach unity unless we refine the very definition of power factor. But the refined power factor is then slightly higher than the conventional one. The refined expression for power factor is a function of the load parameters as well as the line characteristics. For an ideal power system (with no line losses), this coincides with the conventional formula. © 2008 IEEE  

This paper presents a robust control scheme for an islanded microgrid in the presence of structured uncertainties. The microgrid consists of parallel connection of two Distributed Generation (DG) units and a passive load. The DG units are connected to the passive load by using the power electronics converters. The microgrid model is structurally uncertain due to the large perturbations in the load parameters. To deal with the uncertainties, a Linear Fractional Representation (LFR) of the parametrically uncertain system is obtained. To achieve robust performance, the μ-synthesis approach is applied to the derived LFR model to design a μ controller. The resultant controller is structurally... 

The relative vulnerability of spinal motion segments to different loading combinations remains unknown. The meta-analysis described here using the results of a validated L2-L3 nonlinear viscoelastic finite element model was designed to investigate the critical loading and its effect on the internal mechanics of the human lumbar spine. A Box-Behnken experimental design was used to design the magnitude of seven independent variables associated with loads, rotations and velocity of motion. Subsequently, an optimization method was used to find the primary and secondary variables that influence spine mechanical output related to facet forces, disc pressure, ligament forces, annulus matrix...