A photoacoustic gas sensor device for deter-mining a value indicative of a presence or a concentration of a component in a gas comprises a substrate and a measurement cell body, the substrate and the measurement cell body defining a measurement cell enclosing a measurement volume. A reflective shield divides the measurement volume into a first volume and a second volume. An opening in the measurement cell is provided for a gas to enter the measurement volume. In the first volume and on a front side of the substrate are arranged: An electromagnetic radiation source for emitting electromagnetic radiation through an aperture in the reflective shield into the second volume; and a pressure transducer communicatively coupled to the second volume for measuring a sound wave generated by the component in response to an absorption of electromagnetic radiation by the component. At least a portion of a surface of the reflective shield facing the second volume is made of a material reflecting electromagnetic radiation.

A photoacoustic gas sensor device for deter-mining a value indicative of a presence or a concentration of a component in a gas comprises a substrate and a measurement cell body, the substrate and the measurement cell body defining a measurement cell enclosing a measurement volume. A reflective shield divides the measurement volume into a first volume and a second volume. An opening in the measurement cell is provided for a gas to enter the measurement volume. In the first volume and on a front side of the substrate are arranged: An electromagnetic radiation source for emitting electromagnetic radiation through an aperture in the reflective shield into the second volume; and a pressure transducer communicatively coupled to the second volume for measuring a sound wave generated by the component in response to an absorption of electromagnetic radiation by the component. At least a portion of a surface of the reflective shield facing the second volume is made of a material reflecting electromagnetic radiation.

An ultrasound sub-surface probe microscopy device (1) is provided comprising a stage (10), a signal generator (20), a scanning head (30), a signal processor (50) and a scanning mechanism (16). In use, the stage (10) carries a sample (11) and the scanning M mechanism (16) provides for a relative displacement between the sample (11) and the scanning head (30), along the surface of the sample. The scanning head (30) comprises an actuator (31) configured to generate in response to a drive signal (S.sub.dr) from the signal generator (20) an ultrasound acoustic input signal (I.sub.ac). The generated ultrasound acoustic input signal (I.sub.ac) has at least one acoustic input signal component (I.sub.ac1) with a first angular frequency (ω1). The scanning head (30) further comprises a tip (32) to transmit the acoustic input signal (I.sub.ac) through a tip-sample interface (12) as an acoustic wave (W.sub.ac) into the sample. Due to a non-linear interaction in the tip-sample interface (12) at least one up mixed acoustic signal component (W.sub.ac2) in said acoustic wave that has a second angular frequency (ω2) higher than the first angular frequency (ω1) Contrary to known approaches, the sensor signal (S.sub.sense) provided by the sensor facility is indicative for a contribution (W′.sub.ac2) of the at least one up mixed acoustic signal component in reflections (W′.sub.ac) of the acoustic wave within the sample (11). Therewith a relatively high resolution can be achieved with which subsurface features can be detected.

A rotational speed detecting device that detects an engine rotational speed includes: a frequency estimation unit for estimating a frequency of vehicle interior sound as an estimated frequency based on a period of the vehicle interior sound detected by a microphone; an analysis frequency band setting unit for setting an analysis frequency band based on the estimated frequency; a frequency detection unit for performing spectrum analysis of the vehicle interior sound by discrete Fourier transform in the analysis frequency band and detecting the frequency of the vehicle interior sound as a detection frequency; and a rotational speed calculation unit for calculating an engine rotational speed based on the detection frequency.

A rotational speed detecting device that detects an engine rotational speed includes: a frequency estimation unit for estimating a frequency of vehicle interior sound as an estimated frequency based on a period of the vehicle interior sound detected by a microphone; an analysis frequency band setting unit for setting an analysis frequency band based on the estimated frequency; a frequency detection unit for performing spectrum analysis of the vehicle interior sound by discrete Fourier transform in the analysis frequency band and detecting the frequency of the vehicle interior sound as a detection frequency; and a rotational speed calculation unit for calculating an engine rotational speed based on the detection frequency.

An elastic matrix determination method for a laminated iron core, which can optimally determine a shear modulus in two planes including a laminating direction of the laminated iron core included in an elastic matrix in a constitutive equation representing a stress-strain relationship used for vibration analysis, and also provided is a vibration analysis method. When performing a vibration analysis of a laminated iron core formed by laminating steel sheets using a constitutive equation representing a stress-strain relationship in a matrix representation, a shear modulus in two planes including a laminating direction of the laminated iron core included in an elastic matrix in the constitutive equation is determined depending on an average tightening pressure in the laminating direction of the laminated iron core.

A method for determining a quality of a friction stir welded seam is described. The method involves applying an impact to a welded plate and comparing its damping capacity with the damping capacity of a geometrically equivalent defect-free plate. Damping capacities that differ by a small percent difference indicate that the welded plate is also defect-free. This method is particularly advantageous when dealing with small defects, which produce miniscule changes in natural frequency which may not be measureable.

Systems and methods for improved ultrasonic testing are provided. An ultrasonic testing system can include an ultrasonic probe and an ultrasonic controller in electrical communication with the ultrasonic probe. The ultrasonic probe can include a plurality of ultrasonic transducers. The ultrasonic controller can be configured to generate one or more driving signals operative to cause the plurality of ultrasonic transducers to generate respective ultrasonic waves. A combination of the ultrasonic waves can form an ultrasonic waveform having one or more characteristics specified by the one or more driving signals. The ultrasonic controller can be further configured to change the one or more driving signals to adjust at least one characteristic of the ultrasonic waveform.

Systems and methods for improved ultrasonic testing are provided. An ultrasonic testing system can include an ultrasonic probe and an ultrasonic controller in electrical communication with the ultrasonic probe. The ultrasonic probe can include a plurality of ultrasonic transducers. The ultrasonic controller can be configured to generate one or more driving signals operative to cause the plurality of ultrasonic transducers to generate respective ultrasonic waves. A combination of the ultrasonic waves can form an ultrasonic waveform having one or more characteristics specified by the one or more driving signals. The ultrasonic controller can be further configured to change the one or more driving signals to adjust at least one characteristic of the ultrasonic waveform.

A vibration sensor with monitoring function is provided, which includes a substrate, a microelectromechanical vibration sensor chip and an application-specific integrated circuit chip. The microelectromechanical vibration sensor chip is disposed on the substrate and detects a vibration applied to an object to generate a plurality of vibration signals. The application-specific integrated circuit chip is disposed on the substrate and electrically connected to the microelectromechanical vibration sensor chip, which includes a sampling module, a transform module and an analysis module. The sampling module receives and converts the vibration signals into a plurality of digital signals, and filters the digital signals to generate a plurality of time-domain data. The transform module transforms the time-domain data into a frequency-domain data according to a predetermined number. The analysis module executes a comparison process to compare the frequency-domain data with a predetermined spectrum feature table and generates a notification signal according to the comparison result.