On the Alber equation for shoaling water waves

The problem of unidirectional shoaling of a water-wave field with a narrow energy spectrum is treated by using a new Alber equation. The stability of the linear stationary solution to small non-stationary disturbances is analysed; and numerical solutions for its subsequent long-distance evolution are presented. The results quantify the physics which causes the gradual decay in the probability of freak-wave occurrence, when moving from deep to shallow coastal waters.

Adaptive concept of state estimation with incomplete state vector measurement

The paper presents the design and simulation experiments of the adaptive approach in the estimation of the object state realized by filter whose gain is calculated on-line. The adopted concept of determining the gain uses a defined for this purpose signal called an error and on the basis of its waveform features introduces an incremental correction of the amplification factor of the estimation filter. The obtained results of state estimation are characterized by stability and strong correctness even for cases of non-stationary disturbances

Effects on lifetime of low voltage conductors due to stationary power quality disturbances

<p>This paper presents a methodology to estimate the effects of heating and lifetime in Low Voltage conductors (LV) due to the presence of stationary power quality disturbances. Conductor overheating and cable insulation accelerated aging can be caused by temporary increases in the rms values of the voltages and currents due to stationary disturbances. Waveform distortion, unbalance and phase displacements can be considered among the stationary disturbances. For disturbances with short duration, there is no significant reductions in the insulation lifetime, but disturbances acting for long time periods will cause cumulative and detrimental effects. Currently valid models for insulation aging are employed; the expected power quality disturbance levels are extracted from power quality data bases. A discussion about the effects on insulation lifetime is presented.</p>