Nila Montbrun

Burst mode dither control of automotive brake squeal

Brake squeal is an annoying phenomenon, generally occurring when vehicles brake at slow speeds. Significant effort is expended by the automotive industry to avoid squeal during the development of brake systems. Nonetheless, expensive warranty claims still occur when such efforts are not completely successful. Recent research demonstrated that introducing dither control into a brake is an effective means of suppressing squeal. Dither control is a method by which high‐frequency disturbances are introduced into a system. This suppresses the friction induced squeal response at lower frequencies, thus eliminating the audible brake squeal. Dither control, when applied at a 100% duty cycle, is an effective means of suppressing brake squeal. This presentation focuses on the potential to use burst mode dither control for squeal suppression. Burst mode dither control is characterized by duty cycles of less than 100%. Dither is introduced to a brake by placing a piezoelectric stack actuator in the piston of a floati...

Environmental pollution and noise control of two power generator sets placed into a recreation area

This paper deals with the noise control of two power generator sets of 545 kW each, located in a Venezuelan resort. The generator sets made a noise level of 73 dB(A) at a distance of 47 m from the source, where are located the guest rooms. This level was far from the legal regulations for allowable environmental conditions. A noise enclosure with air silencers was proposed to reach a final level of 53 dB(A) at the guest accommodations. Two aspects must be taken into account, the noise reduction and the ventilation specifications of the generator sets, in order to keep the operational temperature. The final noise level was measured at 54 dB(A) and the pressure loss of the silencers was well placed into the ventilation specifications.

A mathematical model for the evaluation and prediction of the mean energy level of traffic noise in Caracas

The increase of the population in capital cities has provoked a serious increase in the acoustical pollution, where the real cause is the traffic noise. Over ten years, sound levels have been measured in several points in the city of Caracas. The main objective was to establish a mathematical model for the mean energy level of traffic noise. This model is a modification and improvement of the model that was used in Germany and Italy. Parameters of the fundamental equations were obtained by the use of large experimental data. In the particular case of Venezuela, an innovation was introduced by the consideration of the motorcycle noise. The obtained model can be used to predict noise pollution in cities and contour maps can be made as well.