Abstract: The invention relates to an electroaeroacoustic source (2) placed in a flow (V) or at the edge of a flow, consisting of an electrodynamic or electromagnetic motor means (5) generating an oscillating motion, and an element (3) coupled to the motor means (5) obstructing the flow so as to exert a dynamic action on said flow. This source can be used to produce an electroaeroacoustic system for the active noise control, particularly in a confined flow.

Abstract: An electromechanical actuator for controlling a flow modulator which is pivotally mounted in a pipe to cause a rapidly variable head loss in a fluid flowing therein, the actuator being provided with a stator and a rotor. The rotor can move only through a predetermined angular sector by oscillating about an angular reference position, and a return device is provided for storing the kinetic energy of the rotor and flow modulator during angular deceleration of the rotor and at least partially returning the kinetic energy to the actuator during angular acceleration of the rotor.

Abstract: An inlet or exhaust line for a reciprocating machine attenuates the sound level of the machine while being simple and economical to produce. A sensor measures the instantaneous flow rate of gases passing through the line while a restriction device variably restricts the cross-section of the line as a function of the instantaneous flow rate measured by the sensor. Material for absorbing acoustic energy covers the internal wall of the line.

Abstract: A measurement method of measuring the unsteady flow of velocity of a fluid, characterized by the fact that it comprises the following steps: i) detecting instants at which the acceleration of the fluid is zero; ii) defining a measurement of the fluid velocity at instants where the acceleration is zero; and iii) determining changes in velocity between instants of zero acceleration by numerically integrating the difference between two static pressures.

Abstract: The invention relates to a device for eliminating sudden changes of pressure in a ventilated or air-conditioned vehicle, the device comprising: a detector for detecting changes in the pressure outside the vehicle and delivering signals representative of said changes; closure means for closing an outside air suction duct and an inside air rejection duct; a control unit receiving the signals from the detector and controlling closure of the ducts above a first determined rate of change in outside pressure, said unit also controlling re-opening of the ducts after said change in outside pressure has fallen below a second determined rate; and means for balancing the inside pressure and the outside pressure by a controlled flow of air between the outside and the inside of the vehicle, said means constraining the pressure inside the vehicle to change as a function of time at less than a set rate.