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In certain operating conditions, the oil-film forces, by which the hydrodynamic bearings act on the rotor, destabilize and induce a self-excited vibration. There are many solution based on modifications of the bearing geometry to enlarge the operational range of the hydrodynamic bearing as a tilting pad bearing, lemon bore, etc. or usage of the dampers whose operation is based only on the dissipation of mechanical energy. In this paper several concepts based on controlled kinematic excitation of the bearing shells is investigated by computer simulation and by experimental test. The mathematical model of the uncontrolled and controlled rotor system contains the nonlinear hydrodynamic forces determined by the solution of the Reynolds equation assuming short case of bearing. To solve the equation of motion the Runge-Kutta method of the 4th order with Dormand-Prince modification and variable length of the integration step is used. The computer simulations were performed for rotor system without feedback control and with feedback controller. The main objectives of the numerical analysis were determination of the stability regions of the vibration excited by the imbalance forces. Results of the computer simulations proved that the analyzed approaches reduce amplitude of the rotor vibration caused by the imbalance forces. Experimental test and computer simulations demonstrate that the active vibration control increases considerably the rotation speed when the self-excited vibration of the oil-film occurred. [ABSTRACT FROM AUTHOR]

• The introduction of new energy performance indicators of road lighting. • The presentation of energy performance indicators as vectors in Cartesian space. • The usefulness presentation of novel energy performance indicators of road lighting. One of the aims of the modernization of the existing road lighting installations is to improve their energy efficiency. EN 13,201–5 standard introduces energy performance indicators for road lighting installations which only take into account active power. Real installations of road lighting do not only experience active power flow, but also reactive power and distortion power flows. This is due to the non-linear current-voltage characteristics of luminaires. Moreover, the use of LED technology has changed the power factor of a luminaire from inductive to capacitive. The paper proposes the introduction of new energy performance indicators: the reactive power density indicator D Q , the annual reactive energy consumption indicator D EQ , the distortion power density indicator D H and the annual distortion energy consumption indicator D EH. The energy performance indicator D P and the new D Q and D H indicators can be presented as coordinates in the Cartesian space in the form of a vector which is interpreted as an indicator of the total energy performance. The use of the proposed indicators in the road lighting design will enable the selection of the best lighting design variant in terms of the electrical power quality, especially if the compared luminaires have a similar or identical active power. [ABSTRACT FROM AUTHOR]