The disclosure discloses a stress gradient high-efficiency non-destructive detection system based on frequency domain calculation of broadband swept frequency signals, and a detection method thereof. The detection method includes: step 1: calibrating an LCR wave velocity of an object to be measured; step 2: calculating a starting frequency and a cut-off frequency of broadband swept frequency signals based on the LCR wave velocity of the object to be measured in the step 1 and a stress gradient measuring range in a depth direction of the object to be measured; step 3: converting phase delay to time delay information based on the phase delay of the starting frequency and the cut-off frequency in the step 2; and step 4: determining stresses of depths corresponding to different frequency components based on the time delay information in the step 3 to finally realize layer-by-layer scanning of stresses at different depths of the measured object. The disclosure is used to solve the problem of low stress gradient measuring accuracy, and realize the high-efficiency characterization of the stress gradient in the depth direction.

An electronic device may include air input sensors that gather air input from a user's fingers, a stylus, or other object in a volume of air near the electronic device. The air input sensors may include ultrasonic transducers that emit ultrasonic signals towards the volume of air and that detect the ultrasonic signals after the signals reflect from the external object. Using time-of-flight measurement techniques, control circuitry may track the movement of the external object in the volume of air near the electronic device. A display may provide visual feedback of the air input, such as shadows that preview where the input will be directed to on the display. The volume of air where input is detected may be divided into multiple input zones that trigger different actions from the electronic device. The ultrasonic transducers may include acoustic lenses.

According to one embodiment, an ultrasonic probe includes a first vibrating element and a second vibrating element. The first vibrating element is configured to vibrate at a first peak frequency. An intensity of a vibration of the first vibrating element is highest at the first peak frequency. The second vibrating element is configured to vibrate at a second peak frequency lower than the first peak frequency. An intensity of a vibration of the second vibrating element is highest at the second peak frequency.

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.

Ultrasonic pulse velocity (UPV) is an extremely important parameter for the assessment of strength of concrete structures and study of elastic properties. ASTM international standard: (ASTM: C597-09) covers the determination of the propagation velocity of longitudinal stress wave pulses through concrete. The suggested method involves transmission of longitudinal ultrasound by transmitting transducer and receiving by a suitable similar transducer. The transit time-measurement and the associated triggering pulses must provide the overall time-measurement resolution of at least 1 μs. The present invention relates to the design of ultrasonic pulse velocity measuring device capable to generate ultrasound preferably in the solid materials including concrete or material supporting the propagation of ultrasound and precisely measure the ultrasonic propagation delay time commonly known as the transit time. The present invention relates to an improved design of an ultrasonic transit time measurement device having provision for automatic pulse threshold error correction. The invention also discloses the method to realize fast counting for the generation of high resolution with relatively slower microcontrollers. The accuracy in the transit time measurement is relatively improved by subtracting the threshold corrected zero offset (without material under test) from the threshold corrected transit time (with sample).

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.

The disclosure discloses an air-coupled ultrasonic detection method and device based on a defect probability reconstruction algorithm. The method includes the following steps: determining the excitation frequency of a transmitting air-coupled transducer according to a frequency dispersion curve of guided waves and the thickness of a to-be-detected piece; determining the group velocity of an antisymmetric mode according to the excitation frequency, and determining the inclination angle of the transmitting/receiving air-coupled transducer according to the Snell law; obtaining an initial waveform of a defect-free test piece as reference data by adopting a same-side penetration method, then rotating the transmitting/receiving transducer by 360 degrees by taking the Z direction as an axis at preset angle intervals by adopting a rotary scanning method, collecting N groups of signal data of the to-be-detected piece again, comparing the N groups of signal data with the reference data to determine whether the signal characteristics have great changes or not, calculating the defect distribution probability on the to-be-detected piece, and carrying out defect imaging on a rotating coverage area of the transmitting/receiving air-coupled transducer according to the defect distribution probability. According to the method, the precision of traditional air-coupled ultrasonic X and Y scanning detection is improved, and compared with a complex imaging technology, the air-coupled ultrasonic detection method consumes less time.

Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also include array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool wave.

Methods for processing data acquired using ultrasound elastography, in which shear waves are generated in a subject using continuous vibration of the ultrasound transducer, are described. The described methods can effectively separate shear wave signals from signals corresponding to residual motion artifacts associated with vibration of the ultrasound transducer. The systems and methods described here also provide for real-time visualization of shear waves propagating in the subject.

A system includes: an acoustic exciter; a compliant material applied to the acoustic exciter to configure the acoustic exciter for triggering acoustic excitation of at least part of a substrate; a sensor configured to receive an acoustic response of the acoustic excitation; and circuitry configured to determine at least one characteristic of the substrate using the acoustic response.