In this paper, a new concept on PI design for time delay systems is introduced. The concept is weighted geometrical center of the stabilizing controller parameters region. Calculating of the stabilizing control parameters region is based on plotting the stability boundary locus in the (kp, ki) plane and then computing stabilizing values of the parameters of a PI controller. The weighted geometr...

Thermosolutal convection in a square cavity filled with air and submitted to an inclined magnetic field is investigated numerically. The cavity is heated and cooled along the active walls with a mass gradient whereas the two other walls of the cavity are adiabatic and insulated. Entropy generation due to heat and mass transfer, fluid friction and magnetic effect has been determined in transient...

On the basis of the state–space method (SSM), a novel linear mathematical model of the unsteady flow for the tailrace system with an open channel is proposed. This novel model is an elastic linearized model of water hammer. The validity of the model has been verified by several examples of numerical simulation, which are based on a finite difference technique. Then, the complete mathematical mo...

We consider oscillators consisting of a reactance circuit and a negative resistor. They may happen to have multi-mode oscillations around the anti-resonant frequencies of the reactance circuit. This kind of oscillators can be easily synthesized by setting the resonant and antiresonant frequencies of the reactance circuits. However, it is not easy to analyze the oscillation phenomena, because th...

This paper focuses on the transient analysis of nonlinear dispersion of a pollutant ejected by an external source into a laminar flow of an incompressible fluid in a channel. The influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation, and the nonlinear governing equations of momentum and pollutant concentration are obtained. The pro...

In the last years there has been a considerable increase in electricity consumption and generation from renewable sources, especially wind and solar photovoltaic. This phenomenon has increased the risk of line saturation with the consequent need of increasing the capacity of some power lines. Considering the high cost and the time involved in installing new power lines, the difficulty in acquir...

Natural convection in an inclined rectangular cavity filled with air is numerically investigated. The cavity is heated and cooled along the active walls whereas the two other walls of the cavity are adiabatic. Entropy generation due to heat transfer and fluid friction has been determined in transient state for laminar natural convection by solving numerically: the continuity, momentum and energ...

Aim of this study is to numerically examine the effect of tonsillectomy on production of Czech vowels /a/ and /i/. Similar experimental studies are not easily realisable on living subjects. The finite element (FE) models of the acoustic spaces corresponding to the human vocal tract for the Czech vowels /a/ and /i/ and acoustic space around the human head are used in numerical simulations of pho...

In this study, the authors use the finite element method to model and analyse a cylindrical copper shelled SLA electrode for EDM operations, which is investigated experimentally in literature. A uniform silver paint thickness and copper shell thickness is assumed around the SLA epoxy core. In the experiment, 2-D analysis was used due to the axissymmetric shape, and steady state and transient di...

The paper presents the transient analysis of a 1.7 MVA wind-power doubly fed induction generator (DFIG) connected to the network and controlled by modified direct torque control during power system disturbances. The finite element model of DFIG is coupled with circuit models of frequency converter, transformer, network and control part in Matlab-Simulink. The transient currents and electromagne...