Ultrasonic Evaluation of the Impact Damage of Polymer Bonded Explosives

The damage properties of polymer bonded explosives under dynamic loading were studied by using ultrasonic evaluation. Explosive samples were damaged by a low-velocity gas gun at different impact velocities. Ultrasonic examination was carried out with a pulse through-transmission method. Spectra analyses were carried out by using fast Fourier transform. Characteristic ultrasonic parameters, including ultrasonic velocities, attenuation coefficients, spectra area and master frequency, were obtained. The correlation between the impact damage and ultrasonic parameters was analyzed. A damage coefficient D was defined by considering a combination of ultrasonic velocity and amplitude. The results show that ultrasonic parameters can be used to quantitatively assess the damage extent in impacted plastic bonded explosives..

Evaluation of fracture damage of SUS306 structural steel using ultrasonic testing

High frequency ultrasonic nondestructive testing was conducted using a direct contact method for SUS306 stainless steel treated by high temperature and fracture tensile tests. Reflected ultrasonic echoes were analyzed. The relationships between the ultrasonic attenuation coefficient, strength of backscattering wave and the elongation at break of the samples were obtained. The damages were evaluated by using these results together with the analysis of microstructure and mechanics of the tested material.

Ultrasonic elastography in clinical quantitative assessment of fatty liver

AIM: To investigate the clinical application of ultrasonic elastography in quantitative assessment of fatty liver grading. METHODS: A total of 105 patients with fatty liver were divided into mild group (n = 46), moderate group (n = 39), and severe group (n = 20). Forty-five healthy individuals served as a normal control group. All patients who underwent routine ultrasound scan and further ultrasonic elastography were evaluated accordingly to the evaluation standards for ultrasonic elastography. The ratio of surface areas of blue region/total surface area in the desired region was measured. RESULTS: Ultrasonic elastography technique, in comparison to traditional ultrasound, had a rather high consistence in grading of fatty liver [κ value = (95.3%63.6%)/(1%-63.6%) = 0.87, P = 0.001]. The score of ultrasonic elastography increased with the severity of fatty liver with a sensitivity of 97.14% and a specificity of 91.11%. A significant difference was found in the ratio of surface areas of blue regions between different groups (P < 0.05).CONCLUSION: Ultrasonic elastography can be used in quantitative assessment of the severity of fatty liver.

Non-collinear nonlinear properties of steel and LY12 aluminum alloy

The sensitivity of collinear nonlinear nondestructive testing technique based on harmonic detection is high,but the results are vulnerable to interference from other nonlinear of experiment sources,which leads to this technology limited in industrial applications.To solve this problem,a non-collinear nonlinear ultrasonic testing experimental system is established based on non-collinear beam mixing technology.The non-collinear nonlinear response is observed in the steel and LY12 aluminum alloy.The results show that:1 Based on the benefits of space selection,mode conversion,frequency and steerable optional of non-collinear beam mixing technology,the interference of system nonlinear effects can be suppressed effectively;2 Mode conversion and beam mixing are present in steel and LY12 aluminum alloy,and the non-collinear non-linear response of LY12 aluminum alloy is stronger than steel and the measurement results are more obvious;3 The technology has the feasibility to evaluate the uniformity of material internal.

Characterization of surface damage of a solid plate under tensile loading using nonlinear Rayleigh waves

This letter reports experimental observation of a direct correlation between the acoustic nonlinearity parameter (NP) measured with nonlinear Rayleigh waves and the accumulation of plasticity damage in an AZ31 magnesium alloy plate specimen.Rayleigh waves are generated and detected with wedge transducers,and the NPs are measured at different stress levels.The results show that there is a significant increase in the NPs with monotonic tensile loads surpassing the material’s yielding stress.The research suggests an effective nondestructive evaluation method to track the surface damage in metals.

Prediction of mechanical ventilation outcome by early abdominal-visceral-blood-flow-and-function score in critically ill patients after cardiopulmonary bypass in the ICU: A prospective observational study

Background:Abdominal organs are important organs that sense and respond to ischemia and hypoxia,but there are few evaluation methods.We use ultrasonography to evaluate abdominal organ function and blood flow in patients with mechanical ventilation(MV)after cardiopulmonary bypass and to obtain a semiquantitative score for abdominal organ function and blood flow.Methods:Patients with cardiopulmonary bypass in the Critical Care Department of Peking Union Medical College Hospital in China from March to July 2021 were enrolled in this prospective observational study.The correlation of the abdominal-visceral-blood-flow-and-function score(AVBFS)with the duration of MV,number of days spent in the intensive care unit(ICU),acute physiology and chronic health evaluation II(APACHE-II),sequential organ failure assessment(SOFA),lactate,epinephrine,and norepinephrine use was analyzed,and the results were used to assess the predictive value of the receiver operating characteristic curve(ROC)regression analysis score for the duration of MV.Results:Of the 92 patients who underwent cardiopulmonary bypass,41 were finally included.The AVBFS were significantly correlated with the duration of MV,number of days spent in the ICU,APACHE-II score,SOFA score,and norepinephrine use time.The AVBFS in a group of patients using ventilators≥36 h were significantly higher than those obtained for a group of patients using ventilators<36 h(P<0.05).The evaluation results for the AVBFS at 0-12 h after ICU admission were as follows:area under the ROC curve(AUC)=0.876(95%confidence interval[CI]:0.767 to 0.984),cut-off value=2.5,specificity=0.842,and sensitivity=0.773.Conclusions:Abdominal visceral organ function and blood perfusion can be used to evaluate gastrointestinal function.It is related to early and late extubation after cardiac surgery.