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Structure-property relationships in bulk materials can be important in establishing sensing methods to assess the state of material microstructure. This is particularly true for nuclear graphites since these materials can display anisotropy and can become oxidized under service conditions. Both anisotropy and oxidation-induced porosity can influence structural integrity and this must be confirmed...
We have studied C-mode and B-mode imaging using high-frequency ultrasonic waves through a thin fiber for direct observation of the microscopic image of tissue. We reported previously that the C-mode images of the tissue on the glass and B-mode image of animal bone placed in water were obtained using a fused quartz fiber as the needle-type ultrasound probe. In this paper, we propose a method for the...
The ability to measure perfusion rates of tissues in a non-invasive and label-free way could enable powerful diagnostic applications to peripheral vascular disease, ischemia, tumor hypoxia, ulcer characterization, and general tissue health. However, current medical techniques of measuring perfusion rates, which include contrast-enhanced ultrasound imaging, perfusion MR imaging require contrast agents...
We present an ultrasonic transit-time gas flow meter (UFM) that features a 40-kHz 2D-phased array for transmitting ultrasonic sound waves up- and downstream to two single element receivers. This allows us to electronically compensate for the well-known parasitic sound drift effect, and, thus, increasing the measurement range by improving the signal-to-noise-ratio (SNR). A regular double-path UFM consists...
An exhaustive monitoring of an internal sulphate attack of Portland cement-based materials is addressed. Four series of Portland cement mortars with different amounts of gypsum (0%–2% SO3 respect to the cement by mass) were monitored by means of physical and non-destructive tests, studying specimens with a low expansion rate to examine the sensitivity of the applied techniques. The expansion analysis...
Streaming velocity mainly depends on the intensity and absorption of ultrasound in the media. For high frequencies exceeding 20 MHz the speed of streaming in blood is also affected by scattering effects on the blood cells and contrast agent microbubbles. According to theoretical calculations, 12.2 % increase in streaming velocity for 1 g/l starch concentration rise should be expected. The theory has...
Recent development of the air-coupled sensing technique provides great potential for practical data measurement in the field; however, an improved data analysis method and careful design of test configuration are required to inspect structures appropriately. Impact-echo (IE) is an efficient method to evaluate delamination-like defects in concrete bridge decks. However, practical application of air-coupled...
Based on the success of deep neural networks for image recovery, we propose a new paradigm for the compression and decompression of US signals which relies on a stacked denoising autoencoders. The first layer of the network is used to compress the signals and the remaining layers perform the reconstruction. We train the network on simulated US signals and evaluate its quality on images of the publicly...
For evaluation of aged concrete structure, it is expected to apply ultrasonic nondestructive measurement. Special coupling media with high viscosity made scanning difficult and the application to huge structure was not practical. Our group prototyped a couplant-free probe realizing strong acoustic coupling using high pressure due to Hertzian contact and found a potential to excite longitudinal wave...
Photoacoustic (PA) imaging aims for the reconstruction of acoustic sources that originate in pulsed light absorption. While the speed of sound (SOS) in biological tissue is heterogeneous, standard reconstruction algorithms usually assume a constant SOS. This results in deformations of the reconstructed sources, which are referred to as aberration and can have a severe impact on the spatial resolution...
Measurement of transducer impedance in ultrasound systems indicates both the performance of a transducer and the presence of damaged elements and cables. Load impedance analysis is typically performed with dedicated test equipment and is a time consuming and thus expensive process, especially for high channel count systems. This paper proposes a method for the measurement of channel source impedance...
In many industrial technological processes, liquids are subjected to high pressures, e.g., in the high pressure food preservation. Similarly, in modern fuel injection systems for diesel engines, biofuel is subjected to a pressure up to 300 MPa. In such conditions, in liquids, high-pressure phase transitions (solidification) can occur that substantially increase the density and liquid viscosity. This...
The drilling process is generally costly and time consuming and prone to serious hazards. Cost-efficiency and enhanced safety measures are vital for any drilling operation. Recent studies indicate that poor reliability in the drilling process resulted in as much as 30% loss of production time. Improved sensor technology with process automation can improve process performance and safety. During drilling...
Second harmonic imaging relies on the double the transmit frequency being generated as the waves propagate into the tissue. The method requires good control over the transmit system, to suppress 2nd harmonics transmitted from the transducer. These transmitted harmonics may originate from both linear, e.g. sidebands in the transmit spectrum, and nonlinear effects in the transducer and transmitting...
An ultrasonic array system is designed for wirelessly powering and communicating with implantable medical devices. A flexible hardware interface is used to drive a 32-element linear phased array with emphasis on programmability and efficiency rather than bandwidth or peak power. Various beam patterns and data modulation schemes are verified at a depth of 6 cm in a tissue phantom with more than sufficient...
Ultrasonic sensor has been widely used, ranging from underwater communication to many aspects, such as medical imaging and therapy. Compared with the traditional piezoelectric sensors, Capacitive micro-machined ultrasonic transducer(CMUT) have advantages of wide band, easy to integration, good consistency and low cost, which make it a research hotspot in the field of ultrasound. As the core of the...
In pulse compression using an M-sequence, the M-sequence modulated signal is transmitted and the received signal is correlated with the transmitted signal. However, the M-sequence modulated signal reflected from a moving object is Doppler-shifted. The Doppler-shifted M-sequence modulated signal cannot be correlated with the transmitted signal. Therefore, Doppler velocity estimation from a cyclic M-sequence...
In this study, a new approach for characterizing material damage using ultrasonic waves is proposed. Four concrete cubes were subjected to different uniaxial loads (0 %, 25 %, 50 % and 75 %) and evaluated using a novel Recurrence Plot Quantification Analysis (RQA) method. This brand new technique was compared to traditional ultrasonic measures: propagation velocity and attenuation. Both the traditional...
Recently, the maintenance of aging structures such as steel bridge has become an important subject. For example, it is reported that corrosion occurred in a steel plate have broken the steel plate. So, development of the measurement method for residual thickness is desired.
Automated tow placement has become a widely-used fabrication technique, especially for large aerospace structures. Robotic heads lay down strips (tows) of pre-impregnated fiber along programmed paths. The intention is to lay adjacent tows abutted to one another, but sometimes a gap is left between a tow and the previously-placed tow. If a tow gap exists, it fills with resin during cure, forming a...
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