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].

Method and processor for time-domain processing of a waveform signal are disclosed. The method includes filtering, by employing one or more cut-off frequency values, the waveform signal for generating the first portion and the second portion, acquiring a frequency shift value, generating a modulated signal having a first frequency portion and a second frequency portion and where the one or more cut-off frequency values have been determined for ensuring that the first frequency portion and the second frequency portion are non-overlapping portions of the modulated signal, and generating the modified signal using the first frequency portion.

Method and processor for time-domain processing of a waveform signal are disclosed. The method includes filtering, by employing one or more cut-off frequency values, the waveform signal for generating the first portion and the second portion, acquiring a frequency shift value, generating a modulated signal having a first frequency portion and a second frequency portion and where the one or more cut-off frequency values have been determined for ensuring that the first frequency portion and the second frequency portion are non-overlapping portions of the modulated signal, and generating the modified signal using the first frequency portion.

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.

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.

An exciter (11, 12) induces an elastic wave in a test object by sequentially giving the object multiple kinds of vibrations having different frequencies. An illuminator (13, 14) performs stroboscopic illumination on a measurement area on the surface of the object. A displacement measurer (15) controls the timing of the stroboscopic illumination with respect to the phase of the elastic wave for each kind of vibration to perform a batch measurement of the displacements, in the off-plane direction of the surface, of the points within the measurement area at least at three different phases of the elastic wave, using speckle interferometry or speckle-shearing interferometry.

The embodiments disclosed herein relate to the examination of gemstones including diamonds, both cut/polished and rough, using the technology of Resonant Ultrasound Spectroscopy. The resonant frequencies are obtained by mechanically causing the stone to vibrate using a swept sine oscillator, sensing the resonance vibrations, and displaying the spectrum to yield a pattern describing the stone. The resonance fingerprints can be used to both track an individual stone to verify its integrity or to grade a rough stone to establish potential value.

A sensor with a mechanical waveguide may be characterized using test ultrasonic signals to generate a baseline signature, and the baseline signature may later be used to detect faults in the sensor.

To detect air in a fluid delivery line of an infusion system, infusion fluid is pumped through a fluid delivery line adjacent to at least one sensor. A signal is transmitted and received using the at least one sensor into and from the fluid delivery line. The at least one sensor is operated, using at least one processor, at a modified frequency which is different than a resonant frequency of the at least one sensor to reduce an amplitude of an output of the signal transmitted from the at least one sensor to a level which is lower than a saturation level of the analog-to-digital converter to avoid over-saturating the analog-to-digital converter. The signal received by the at least one sensor is converted from analog to digital using an analog-to-digital converter. The at least one processor determines whether air is in the fluid delivery line based on the converted digital signal.

To detect air in a fluid delivery line of an infusion system, infusion fluid is pumped through a fluid delivery line adjacent to at least one sensor. A signal is transmitted and received using the at least one sensor into and from the fluid delivery line. The at least one sensor is operated, using at least one processor, at a modified frequency which is different than a resonant frequency of the at least one sensor to reduce an amplitude of an output of the signal transmitted from the at least one sensor to a level which is lower than a saturation level of the analog-to-digital converter to avoid over-saturating the analog-to-digital converter. The signal received by the at least one sensor is converted from analog to digital using an analog-to-digital converter. The at least one processor determines whether air is in the fluid delivery line based on the converted digital signal.