An electro-magnetic acoustic transducer (EMAT) having an electromagnet array is provided. The electromagnet array includes electromagnets. Each electromagnet includes a magnetic core and a wound coil wrapped around the magnetic core. The electromagnet array generates bias magnetic fields having different patterns when the wound coils are energized differently. For instance, the electromagnet array generates a bias magnetic field having a given pattern, for the EMAT to transmit a first type of ultrasonic wave such as shear-horizontal wave, when the wound coils are energized in a given manner; and generates a bias magnetic field having a different pattern, for the EMAT to transmit a second type of ultrasonic wave such as a Lamb wave, when the wound coils are energized in a different manner.

An electro-magnetic acoustic transducer (EMAT) having an electromagnet array is provided. The electromagnet array includes electromagnets. Each electromagnet includes a magnetic core and a wound coil wrapped around the magnetic core. The electromagnet array generates bias magnetic fields having different patterns when the wound coils are energized differently. For instance, the electromagnet array generates a bias magnetic field having a given pattern, for the EMAT to transmit a first type of ultrasonic wave such as shear-horizontal wave, when the wound coils are energized in a given manner; and generates a bias magnetic field having a different pattern, for the EMAT to transmit a second type of ultrasonic wave such as a Lamb wave, when the wound coils are energized in a different manner.

The invention relates to a wave-emitting device comprising an electromechanical actuator stimulated by a signal generator that allows it to generate torsional waves with a higher amplitude, and to an ultrasonic transducer comprising said device. The use of said devices allows the reconstruction of the structural characteristics of the materials subject to the waves generated by the emitter device.

The invention relates to a wave-emitting device comprising an electromechanical actuator stimulated by a signal generator that allows it to generate torsional waves with a higher amplitude, and to an ultrasonic transducer comprising said device. The use of said devices allows the reconstruction of the structural characteristics of the materials subject to the waves generated by the emitter device.

A resonance method for a vibration system for resonant vibration of an excitation unit having a vibrating mass includes detecting a deflection of the vibrating mass, differentiating the deflection to form a velocity of the vibrating mass; generating from the deflection and the velocity a mechanical phase position; forming from the mechanical phase position a corrected phase position by using a correction value; forming, based on the corrected phase position, an electrical angular frequency with a P-regulation; integrating the electrical angular frequency to determine an electrical phase position; forming from the electrical phase position a correction factor by using a trigonometric function; and applying the correction factor to an excitation setpoint value to generate a corrected excitation setpoint value. Also disclosed are a converter, an excitation unit having the converter, and a vibration system having the excitation unit and the vibrating mass.

A vibration generation device includes: a base configured to transmit vibration to an object; an arm provided at the base swingably around a rotation axis; and at least one driving unit including a magnet, and a coil disposed to face the magnet in a non-contact manner, and configured to swing the arm. One of the magnet and the coil is disposed at a position separated from the rotation axis at the arm. The arm includes a disposition portion provided at a position separated from the rotation axis at the arm, and a weight portion detachably attached to the disposition portion.

An electromagnetic transducer, including at least one active air gap, wherein the active air gap is a non-axial air gap. In some instances, the electromagnetic transducer of claim further comprises a coil configured to generate a dynamic magnetic field, the coil having a longitudinal axis, wherein the active air gap extends in the direction of the longitudinal axis of the coil.

An electromagnetic transducer, including at least one active air gap, wherein the active air gap is a non-axial air gap. In some instances, the electromagnetic transducer of claim further comprises a coil configured to generate a dynamic magnetic field, the coil having a longitudinal axis, wherein the active air gap extends in the direction of the longitudinal axis of the coil.

An EMAT system (1) for detecting surface and internal discontinuities (2) in thick conductive structures (90) at high temperatures, comprising a magnet (4) that generates a static magnetic field (SMF) and an HF electric coil (6) for inducing, or being induced by, eddy currents in the material (14). It comprises a perforated matrix-array laminated magnetic core (22) placed between the HF electric coil (6) and the inspected material (3), which is made up of a multitude of apertured HF active laminae (29) incorporating a ferromagnetic material, and of apertured insulating passive laminae (53). Trough-holes (41, 57) are drilled through each lamina (29, 53) and form a grooved cylindrical aperture (39). Parallel induced-current loops (43) encircle each magnetic trough-hole (41) of the HF active laminae (29). Cooling means (58) force a heat-transfer fluid (60) to pass through the grooved cylindrical aperture (39).

A sensor includes a radio frequency interrogator, a responsive patch, a radio frequency resonance detector, and a transmission line. The radio frequency interrogator is configured to produce an electromagnetic interrogation pulse having a first frequency. The responsive patch includes a substrate and a resonant layer disposed on a surface of the substrate. The substrate includes a polymer. The resonant layer includes an electrically conductive nanomaterial. The resonant layer is configured to resonate at the first frequency in response to receiving the electromagnetic interrogation pulse. The radio frequency resonance detector is configured to detect a resonating response of the responsive patch. The transmission line couples the responsive patch to the radio frequency resonance detector. The transmission line is configured to transmit the resonating response of the responsive patch to the radio frequency resonance detector.