The invention comprises a device and method to estimate the elasticity of soft elastic solids from surface wave measurements. The method is non-destructive, reliable and repeatable. The final device is low-cost and portable. It is based in audio-frequency shear wave propagation in elastic soft solids. Within this frequency range, shear wavelength is centimeter sized. Thus, the experimental data is usually collected in the near-field of the source. Therefore, an inversion algorithm taking into account near-field effects was developed for use with the device. Example applications are shown in beef samples, tissue mimicking materials and in vivo skeletal muscle of healthy volunteers.

An apparatus for inspecting a well having nested multi-tubular structure, includes: an acoustic transducer conveyed in an inner-most tubular in the structure and configured to receive a return acoustic signal having a plurality of resonances due to the structure; an acoustic impedance matching material disposed on a sensing face of the acoustic transducer; a signal generator that generates a signal having a plurality of frequencies to drive the acoustic transducer; a signal shaper that modifies the signal to provide a drive signal to the acoustic transducer; and a processor configured to determine an annulus distance of any tubular in the structure with respect to an adjacent tubular using a time of flight of a transmitted acoustic signal, an acoustic speed in a component in the nested multi-tubular structure using the annulus distance and the plurality of resonances, and a characteristic of the component that corresponds with the acoustic speed.

Various exemplary embodiments relate to a device to measure carbon dioxide (CO.sub.2) levels, including a first oscillator group comprising a first sensor to measure air pressure, where the first sensor comprises a first sealed membrane, and where the first sealed membrane overlays a sealed first cavity; a second oscillator group including a second sensor to measure the resonance frequency of a second unsealed oscillating membrane, and where the second unsealed membrane overlays a second cavity in contact with the air outside of the second sensor; and a mixer accepting as input a first frequency measurement output from the first oscillator group and a second frequency measurement output from the second oscillator group, outputting the difference of the first frequency measurement and the second frequency measurement, and computing a carbon dioxide measurement based on the difference.

An apparatus for inspecting a well having nested multi-tubular structure, includes: an acoustic transducer conveyed in an inner-most tubular in the structure and configured to receive a return acoustic signal having a plurality of resonances due to the structure; an acoustic impedance matching material disposed on a sensing face of the acoustic transducer; a signal generator that generates a signal having a plurality of frequencies to drive the acoustic transducer; a signal shaper that modifies the signal to provide a drive signal to the acoustic transducer; and a processor configured to determine an annulus distance of any tubular in the structure with respect to an adjacent tubular using a time of flight of a transmitted acoustic signal, an acoustic speed in a component in the nested multi-tubular structure using the annulus distance and the plurality of resonances, and a characteristic of the component that corresponds with the acoustic speed.

To provide a technique for expanding a measurement dynamic range and performing a stable detection in a sensing sensor using a crystal resonator. A spacer is disposed between an oscillator circuit that oscillates a crystal resonator and a base body that cools an oscillator circuit to a cryogenic temperature, and an oscillator circuit board includes a heater resistor that heats the oscillator circuit. Therefore, the temperature of the oscillator circuit that does not fall below a functional limit temperature and is a low temperature as much as possible can be provided. A negative resistance of the oscillator circuit can be increased, the measurement dynamic range can be expanded, and the crystal resonator can be stably oscillated.

An electric measurement circuit possesses an electrical reaction leg for forming an oscillator from a resonator, and furthermore possesses a measurement leg the input of which is supplied by the electrical reaction leg. The measurement leg contains an adjustable phase shifter so that an additional excitation force that is applied to the resonator in the measurement leg can be adjusted in phase quadrature with respect to an excitation force that is applied to the resonator in the electrical reaction leg. Such an electrical measurement circuit is particularly suitable for forming a photoacoustic gas detector.

To provide a technique for expanding a measurement dynamic range and performing a stable detection in a sensing sensor using a crystal resonator. A spacer is disposed between an oscillator circuit that oscillates a crystal resonator and a base body that cools an oscillator circuit to a cryogenic temperature, and an oscillator circuit board includes a heater resistor that heats the oscillator circuit. Therefore, the temperature of the oscillator circuit that does not fall below a functional limit temperature and is a low temperature as much as possible can be provided. A negative resistance of the oscillator circuit can be increased, the measurement dynamic range can be expanded, and the crystal resonator can be stably oscillated.

The invention comprises a device and method to estimate the elasticity of soft elastic solids from surface wave measurements. The method is non-destructive, reliable and repeatable. The final device is low-cost and portable. It is based in audio-frequency shear wave propagation in elastic soft solids. Within this frequency range, shear wavelength is centimeter sized. Thus, the experimental data is usually collected in the near-field of the source. Therefore, an inversion algorithm taking into account near-field effects was developed for use with the device. Example applications are shown in beef samples, tissue mimicking materials and in vivo skeletal muscle of healthy volunteers

In accordance with an embodiment, a MEMS sensor includes a membrane that is suspended from the substrate, a resonant frequency of said membrane being influenced by an ambient pressure that acts on the membrane; and an evaluation device configured to perform a first measurement based on the resonant frequency of the membrane to obtain a measurement result, where the evaluation device is configured to at least partly compensate an influence of the ambient pressure on the measurement result.

A method, a computer program and a system for ultrasonic inspecting of objects is provided. The method comprises positioning (103) a measuring device (11) comprising a plurality of transducers (12) on the inspected object (20) and performing a number of test signal acquisitions (103). Each acquisition includes using one transducer to induce an ultrasonic signal into the test object, and using at least one other transducer to receive an ultrasonic test signal. The inspecting further comprises determining (105, 205) the influence of contact surface variations between each test signal and a reference signal; compensating (106, 206) the full test signal for the contact surface variations; and determining (109) a residual signal. The system comprises a computing device (30), and a measuring system (13) communicatively connected to the computing device (30). The measuring system (13) includes an ultrasound unit (19) and a measuring device (11) provided with a plurality of transducers (12). The computing device (30) comprises a calibrator (303) to determine (105, 205) the influence of contact surface variations, and compensate (106, 206) the test signal. The computing device (30) comprises a residual calculator (304) to determine (109) the residual signal.