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ObjectiveThis study aimed to investigate the accuracy and consistency of different ultrasound protocols for the measurement of gastrocnemius muscle (GM) thickness and to identify a suitable ultrasound scheme that can be used to detect the low muscle mass in older with disability.Materials and methodsIn this cross-sectional study, each participant underwent three different ultrasound protocols for the measurement of the GM thickness, and each measurement was repeated three times. The three measurement schemes were as follows: method A, lying on the examination bed in a prone position with legs stretched and relaxed and feet hanging outside the examination bed; method B, lateral right side lying position with legs separated (left leg flexed and right leg in a relaxed state); and method C, right side lying position with legs together and lower limb muscles in a relaxed state. The low muscle mass was determined by averaging two or three measurements of the GM thickness determined using different sonographic protocols.ResultsThe study included 489 participants. The difference in the prevalence of low muscle mass identified between two and three replicates of the same measurement protocol ranged from 0 to 1.3%. Considering the three repeated measurements of the method A as the reference, the area under the curve (AUC) in different measurement schemes were 0.977-1 and 0.973-1 in males and females, respectively. Furthermore, male and female Kappa values from low to high were 0.773, 0.801, 0.829, 0.839, and 0.967 and 0.786, 0.794, 0.804, 0.819, and 0.984, respectively.ConclusionDifferent ultrasound measurement protocols showed high accuracy and consistency in identifying low muscle mass. Repeating the measurements two or three times was found to be feasible.

To apply Fiber Bragg Grating (FBG) sensors in the hole structural health monitoring of aircraft, this study investigates a temperature compensation algorithm based on Fourier curve-fitting, combined with an analysis of FBG layout. The results identify that the wavelengths have a linear relationship with stress and temperature and the linear correlation coefficients are all greater than 0.9. In the experiment, the temperature range was 17 °C-100 °C (step is 10 °C) and the tensile force changed from 0 N to 10 KN (step is 1 KN). With the Fourier curve-fitting of the wavelength variation, the temperature compensation can be actualized, and the average error of temperature is 0.17 °C. By integrating the algorithm in the self-developed FBG interrogation system, the real-time monitoring of stress is achieved with the average error of stress is 3.9 με.