We investigate the properties of one–dimensional flux “voids” (connected regions in the flux distribution above the mean flux level) by comparing hydrodynamical simulations of large cosmological volumes with a set of observed high–resolution spectra at z ∼ 2. After addressing the effects of box size and resolution, we study how the void distribution changes when the most significant cosmologica...

In this paper a virtual mutual inductance approach is used to analyse the performance of transverse flux machines (TFMs). The virtual mutual inductance between the stator windings and the magnets’ equivalent currents is obtained by integrating the flux produced by the stator windings over the surface of the magnets. Key design parameters such as back EMF, torque, phase inductance and power fact...

For improving the quality of the energy transfer from the power supply to the load, and reducing the harmful effects of the harmonics generated by nonlinear load. We propose a new multi-function converter (MFC) as an efficient solution to improve the power quality. This paper presents a new DPC strategy based on virtual flux Observer and switching table to control PWM rectifier achieving by thi...

Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-...

Full power rating three-level neutral-point clamped (3L-NPC) back-to-back power converters seem promising for wind turbine systems with high power. Direct Model Predictive Control (DMPC) is an attractive technique, in particular, for multi-level converters. Voltage sensorless control makes the voltage measurements obsolete. This work proposes and verifies an Initial Bias Compensation based Virt...

This paper explains the control strategies for three phase PWM rectifier using space vector modulation (SVM).The virtual flux based Direct Power Control (VF-DPC) which eliminates the line voltage measurements, active filtering function along with direct power control and conventional Voltage Oriented Control (VOC) in rotating coordinates with a novel line voltage estimator are studied, modeled ...

Active filters have proven to be more effective than passive techniques to improve power quality and to solve harmonic and power factor problems due to nonlinear loads. This paper proposes a control scheme based on the instantaneous active and reactive power. The inverter of this active filter is a three-phase, two-level converter. Space vector technique is used as modulators and pattern genera...

The objective of this article is to highlight certain features of a number of coefficients that appear in models of phenomena of transport in anisotropic porous media, especially the coefficient of dispersion, the 2nd rank tensor Dij , and the dispersivity coefficient, the 4th rank tensor aijkl , that appear in models of solute transport. Although we shall focus on the transport of mass of a di...