Abstract: This invention refers to an ion mobility spectrometer in a fluid subjected to an electric field and an acoustic wave for the selective detection, classification and quantitative determination of the concentration of charged particles, based on their electrical mobility. The functioning of this device is based on the application of an electric field in a classification region occupied by a fluid. The electric field provokes drift of the charged particles through the classification region. The drifting particles suffer a lateral perturbation in their trajectory due to an oscillatory movement of the fluid in which they are immersed when this is subjected to an acoustic wave. Both the spectrometer and the method of discrimination and detection of the current of charged particles is the object of this invention.

Abstract: This invention refers to an ion mobility spectrometer in a fluid subjected to an electric field and an acoustic wave for the selective detection, classification and quantitative determination of the concentration of charged particles, based on their electrical mobility. The functioning of this device is based on the application of an electric field in a classification region occupied by a fluid. The electric field provokes drift of the charged particles through the classification region. The drifting particles suffer a lateral perturbation in their trajectory due to an oscillatory movement of the fluid in which they are immersed when this is subjected to an acoustic wave. Both the spectrometer and the method of discrimination and detection of the current of charged particles is the object of this invention.

Abstract: The invention relates to a device which can compensate, at origin, the magnetic field perturbations in the surroundings of an electrically-driven train track caused by variations in the current of the power supply catenary. The object of the system is to create a return circuit with a geometry which varies with the position of the train, causing the suppression at origin of the field produced by the catenary-train-track circuit and thus reducing perturbations of the magnetic field in the surroundings. The system relies on shunting the return current from the track divided in to elementary segments insulated from each other, to a return conductor placed near the catenary and parallel to it, using a series of vertical conductors which connect each segment to said return conductor.