Results 1 - 10 of 28
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[en] Methods based on propagation of stress wave phenomena indicate particularly useful in diagnosis of non-metallic materials. The aim of this research is to demonstrate that ultrasonic measurement can produce satisfactory results in predicting certain mechanical properties of standing Aquilaria malaccensis tree. The mechanical information is very important to diagnose the condition inside the trunk. The experiment has been conducted on agarwood samples using a pulse compression ultrasonic system. The apparatus equipped with exponential horn 54 kHz piezoelectric normal probe. Through transmission method of longitudinal ultrasonic wave has been used throughout this experiment to measure velocity of ultrasonic signal through the sample. The result showed that the ultrasonic technique can be used in diagnosing of wood-based samples. (author)
[en] The optimum distance parameters obtained int testing the surface condition of the PEB cladding using a variety of ultrasonic test immersion probes. The use of ultrasonic testing equipment, especially in the PIE activities (Post irradiation examination), is one of the testing methods at the test stage which does not damage nuclear fuel in Radiotherapy Metallurgical Installation of PTBBN-BATAN. The method used is to compare % FSH (Full Screen High) output signal data at certain distance variations (28 -42 mm) on IK-56, IK-5-10, and IW-10-6 probes using PEB cladding samples with 6400 m/s velocity. The result obtained are that each of these probes has an optimum distance of 32 mm, 38 mm, and 32 mm against the sample with highest % FSH on the IK-5-6 probe. So that the optimization of the parameters of the variation of probes on the PEB cladding is normal and result in the probes IK-5-6 being the best probe in interpreting the surface conditions of the PEB cladding if there are defects/anomalies.(author)
[en] We used an ultrasound-enhanced scintillation proximity assay to accurately determine the levels of complement decay-accelerating factor (CD55) for the early detection and assessment of the progression of pleural metastatic lung cancer. We found that the expression of CD55 in metastatic tumor tissues is 2.8 times higher than that in the serum at the early stages. We also found that the concentration of CD55 in serum decreases with the progression of metastasis. These results suggest that CD55 is a potential biomarker for the prediction of pleural metastatic lung cancer. (author)
[en] In this work, microstructural changes during creep of 9Cr-1Mo steel were characterized using ultrasonic and hardness measurements. The creep testing of this steel was firstly performed at 873 K under the initial stresses of 160 and 175 MPa, respectively. Then, eight specimens under each stress level were prepared by the interrupted tests to simulate various creep states. Subsequently, two parameters of ultrasonic attenuation and velocity were introduced by the ultrasonic testing. Experiment results showed that regardless of the stresses, the ultrasonic attenuation experiences a peak at about 20% of the creep rupture time and a minimum value at about 50%, showing a strong correlation between ultrasonic attenuation and the creep life fraction. In addition to a slight increase during the primary creep, the ultrasonic velocity exhibits a significant change during the tertiary creep. Based on the analysis of microstructure changes, it indicated that the ultrasonic attenuation is significantly sensitive to the dynamic changes of the dislocation. In contrast, the velocity is mainly related to the evolution of precipitates. The Vickers hardness decreases monotonously during the creep process and presents a linear relation with the inverse of average diameter of M23C6 carbides during the secondary and tertiary creep. Accordingly, it suggested that the present ultrasonic and hardness measurements provided a convenient tool to evaluate the microstructure evolution during creep degradation of heat-resistant steels.
[en] Low frequency piezocomposite transducers have been used in combination with pulse compression methods to penetrate into concrete-type materials. Ultrasonic Chirp signal with a frequency range 100 - 200 kHz and of 10 ms time duration was used to excite a pair of 54 mm diameter piezocomposite transducers in patch-catch mode. The centre frequency of the signal was 170 kHz. The result shows that some good signals with acceptable frequency were obtained. There was a problem with variability due to the high degree of scattering because the result had changed even with small changes in transducer position. Thus, an additional signal processing method was introduced, whereby the total energy reaching the receiver was calculated as a function of time from the cross-correlation outputs. (author)
[en] A steel plate with periodic stepped resonators immersed in water has been presented to enhance the asymmetric acoustic transmission (AAT) in the present paper. It results from the re-emitted waves at resonance by the cap which would act as a secondary source. By changing the geometrical parameters of the stepped resonator, the AAT phenomenon can be tuned easily. The proposed acoustic system may have potential impact on underwater acoustic and medical ultrasonic devices in sub-wavelength region. (author)
[en] Double-Shell Tank (DST) integrity at Hanford is maintained with a variety of activities such as ultrasonic and visual inspections, chemistry controls, corrosion monitoring and structural analyses methods . A pressing need for the Double-Shell Tank Integrity Program is the ability to inspect the bottom of the tanks. Though the DSTs' annulus spaces (the space between the internal and external tank walls) have been inspected visually since 1992 and with Ultrasonic Testing (UT) since 1996, WRPS has been unable to conduct inspections of the tank bottoms due to limitations of available technology, omitting about 40 percent of the tank surface below the maximum fill level from routine inspection. Visual inspections of the tank annulus have been conducted up to five times in some DSTs and the annulus space for all of the DSTs has been inspected twice with UT. The annulus region includes the walls of the primary tank and secondary liner along with accessible portions of the secondary liner bottom. Due to the lack of under-tank inspection technology, degradation of the primary tank bottom in Tank AY-102 was undetected until the tank leaked into its annulus space, confirmed in 2012 . Since that time, WRPS has been working with the nondestructive examination community and the Pacific Northwest National Laboratory to evaluate potential technologies to conduct these challenging remote inspections. Recent work has included the development, testing, and deployment of several remote visual inspection technologies to observe the condition of the primary tank bottom of the DSTs by leveraging air distribution slots in the refractory pad on which it rests. Robotic solutions to conduct this inspection were developed with a detailed understanding of the physical configuration and operational logistics. Understanding and subsequent communication of these details to vendors within the robotics and nondestructive examination community was a critical component to the successful production of these new tools. In total, two remote visual inspection tools were produced by two vendors. The first tool was designed to leverage existing ultrasonic testing magnetic wall crawler technology in use within the double-shell tank annuli at Hanford. This resulted in a cost savings, immediate familiarization with the equipment, and a more streamlined shop to field experience. The second tool was developed from the ground up, and represents a more tailored and purpose-built solution to the problem. While costlier and more complex, it is also more versatile and capable of future growth or adaptation. Initial design of both tools began in early FY17 with fabrication and testing completed in early FY18. The tools were designed to be deployed alongside existing inspection operations and expand coverage. Development of visual inspection tools to evaluate the primary tank bottom region of the double-shell tanks was planned as the first stage of inspection. Continued development of volumetric sensors and incorporation of these inspection tools into Hanford's ongoing Double-Shell Tank Integrity Program are the next steps, continuously seeking to expand understanding of asset integrity and remaining useful life. (authors)
[en] In the present study, the partial loss and distortion of turbine blades were acoustically detected while the turbine was rotating. An ultrasonic signal of a specific frequency (300 kHz) was transmitted in the form of continuous sine waves to the rotating turbine model. The signal was reflected on the turbine blade and received by a receiver. The amplitude of the given frequency component in the received signal was analyzed by signal processing. Because ultrasounds are attenuated easily when propagated into air and have a straight characteristic like light, the characteristics of the signals were examined by a quantitative test. The signal attenuation with respect to distance and the signal reduction by eccentricity were observed and compared with the experimental results. Partial loss decreased the sound reflection area; thus, the signal amplitude was reduced. The signal amplitude was inversely proportional to the size of the defect. Distortion caused larger eccentricity between the transmitter and the receiver. Weaker signals were detected with the more distorted blade. When the blade was distorted by more than 20 dg, the amplitude of the signal decreased significantly. In short, defects of turbine blades cause a reduction in the acoustic signal. It was verified that acoustic diagnosis can be applied to detect the partial loss and distortion of turbine blades.