A method for detecting faults in plates includes the steps of: transmitting an acoustic signal towards the plate from a transmitting transducer, and receiving the acoustical signal from the plate in a receiving transducer. The receiving transducer is mounted at a distance from the transmitting transducer. The method includes the further steps of identifying zones of the plate wherein energy levels of the received signals are attenuated compared to other zones of the plate, and comparing the energy levels of the A.sub.2 and S.sub.3 guided Lamb modes in the received signals in the identified zones.

A method for determining a measurement error caused by a filling error, in particular the presence of gas bubbles, during measurement of the density of a liquid by means of a densimeter having a flexural resonator containing the liquid to be measured. During a measuring operation, a period duration of an oscillation of the flexural resonator induced by an induction unit is measured by a measuring device and the density of the liquid is determined by an evaluation unit.

A combined vapor and/or gas concentration sensor and switch includes a resonating structure, a first alternating current, AC, voltage source coupled to a drive electrode, the first AC voltage source providing the resonating structure with a first voltage having an amplitude causing a first vibration mode of the resonating structure to exhibit a pull-in band and having a first frequency response adjacent to the pull-in band, where the first frequency response is nonlinear, a second AC voltage source coupled to the drive electrode and providing a second voltage having a frequency so that a second frequency response of the resonant structure, adjacent to a third vibration mode, is linear, and a read-out circuit coupled configured to determine a vapor and/or gas concentration based on a difference between (1) the frequency of the second voltage and (2) a frequency obtained by the read-out circuit from the resonating structure.

A heat flux sensor comprising: an array of nanofilaments suspended with respect to a support, each nanofilament comprising an electrically conducting material, the array being able to be biased by an electric power source to circulate an electric current in each of the nanofilaments, at least one resonator of the nanoelectro-mechanical system (NEMS) type comprising: a beam consisting of a nanofilament forming a side of the array, an actuation device able to generate a vibration of the beam under the effect of an excitation signal, a detection device configured to measure a displacement of the beam during the vibration and emit an output signal having a resonance at the resonant frequency of the resonator, the resonant frequency depending on the intensity of the electric current flowing through the beam, a temperature variation of the array of heating nanofilaments induced by a variation in a characteristic of a fluid surrounding the array causing an intensity variation of the current flowing through the beam resulting in a variation in the resonant frequency of the resonator.

Ultrasonic excitation to a sample is provided with an apparatus including: a cylindrical ultrasonic transducer, and a plate disposed on an end of the cylindrical ultrasonic transducer. The ultrasonic transducer is configured to provide a vertical vibration in operation. A Lamb wave vibration is generated in the plate by the vertical vibration of the ultrasonic transducer. The Lamb wave vibration converges at a central region of the plate, where a sample is disposed. Alternatively, a cylindrical array of ultrasonic transducers can be used instead of a single cylindrical transducer. Such an array can be driven as a phased array for beam shaping and/or multi-focusing.

This method comprises: generating, only using the device, a low-frequency signal that makes the structure vibrate, generating a high-frequency signal in the structure, measuring a vibratory signal caused by the generated low-frequency and high-frequency signals at the same time then adaptively re-sampling these measurements to obtain a re-sampled vibratory signal the power spectrum of which comprises: a first frequency range [u.sub.BFmin; u.sub.BFmax] of width larger than 5 Hz that contains 95% of the power of the low-frequency signal, a second frequency range [u.sub.HFmin; u.sub.HFmax] of width systematically smaller than u.sub.BFmin that contains 95% of the power of the low-frequency signal, signaling a defect in the structure if an additional power lobe is detected outside of the ranges [u.sub.BFmin; u.sub.BFmax] and [u.sub.HFmin; u.sub.HFmax].

Systems and methods are provided for obtaining a flexural-attenuation measurement for cement evaluation that may be effective even for wells with relatively thick casings. A method includes emitting an acoustic signal at a casing in a well that excites the casing into generating an acoustic response signal containing acoustic waves, such as Lamb waves. The Lamb waves include flexural waves and extensional waves. The casing may be relatively large, having a thickness of at least 16 mm. The acoustic response signal may be detected and filtered to reduce a relative contribution of the extensional waves. This may correspondingly increase a relative contribution of the flexural waves. The filtered acoustic response signal may be used as a flexural-attenuation measurement for cement evaluation.

According to one embodiment, a sensor module includes a sensor and a diagnosis circuit. The sensor includes piezoelectric transducers and switches. The piezoelectric transducers have different resonance frequencies. The switches are provided to correspond to the piezoelectric transducers, respectively. Each of the switches outputs an output signal corresponding to a voltage generated by an inverse piezoelectric effect of a corresponding piezoelectric transducer of the piezoelectric transducers. The diagnosis circuit diagnoses, based on a difference in pattern of the output signal, whether vibration has newly occurred in the sensor, and switch an output destination of the output signal of the sensor according to a result of the diagnosis.

An inspection apparatus inspects a pressure vessel using laser ultrasound. The apparatus includes an oscillation device that oscillates an excitation laser for exciting the pressure vessel and a conduit to guide the excitation laser oscillated from the oscillation device to inside the pressure vessel. The conduit is inserted into the pressure vessel with one conduit end located inside the pressure vessel and an opposite end located outside the pressure vessel. The apparatus includes a reflector at one conduit end inside the pressure vessel to reflect the excitation laser guided by the conduit and a detector that detects ultrasonic waves generated in the pressure vessel by the excitation laser reflected by the reflector by oscillating a receiving laser from outside of the pressure vessel. At least the conduit, reflector, or detector moves to correct an optical path of the excitation laser or the receiving laser.

An electro-magnetic acoustic transducer (EMAT) system and method for controlling the EMAT system are provided. The system includes an electromagnet array with one or more 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.