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A rapid and non-destructive ultrasonic pulse echo system was developed for vegetable oils characterization. To understand the differences in the ultrasonic properties of the oils, physical traits, such as their viscosity and density, were related to the ultrasonic data. In turn, these physical traits were correlated with the fatty acid compositions of the oils. Eighty oil samples, including 30 extra virgin olive oil (EVOO), 15 refined olive oil, 15 pomace olive oil, 10 rapeseed oil, 5 sunflower oil and 5 peanut oil samples, were analysed for their sound properties, viscosities, densities and fatty acid compositions. It was observed that the ultrasonic velocity of EVOO decreased linearly with increase in temperature, the temperature coefficient of ultrasonic velocity in EVOO was −2.92 m·s−1·°C−1. The ultrasonic velocity of EVOO (1453 ± 2 m/s) differed significantly from those of pomace olive oil and the oils of other botanical origin, but not from the velocity of refined olive oil. Ultrasonic velocity was positively correlated with the density and negatively correlated with the viscosity of the oils. The higher density and lower viscosity of the oils were in turn related to a higher unsaturation degree of the oils. Hence, oils with a higher proportion of unsaturated fat present higher densities and lower viscosities, which resulted in higher ultrasonic velocity values. Ultrasonic measurements allow rapid, non-destructive analysis, and this first application for characterization of these oils is promising. Unlabelled Image • A rapid and non-destructive ultrasonic pulse echo system was developed for oil characterization. • The ultrasonic velocity of EVOO decreased linearly with increase in temperature. • The ultrasonic velocity of EVOO differed significantly from nearly all other types of oils. • Ultrasonic velocity was positively correlated with the unsaturation degree of the oils. [ABSTRACT FROM AUTHOR]

• We present a new compact complaint U-joint with axial anti-buckling in bidirection. • We improve the compliance matrix of a generic sheet. • We derive the generalized compliance matrix of the joint about its centroid. • We analyse the effect of sheet geometry on the joint's precision and motion range. • We analyse the nonlinearities of the joint by nonlinear finite element analysis. This paper presents a new compliant universal joint using four identical generic sheet flexures (short sheets) and a long wire beam. The compliant joint is compact and in mirror symmetry, and is robust to axial buckling in bi-direction. The compliance matrix of the generic sheet, including a straight sheet and an elliptical-arc-fillet (EAF) sheet, is improved at first. Then a normalization-based analytical model of the universal joint is derived, followed by mobility identification of the joint. The relationships between the straight-sheet joint's compliance and the length, width and thickness of the sheet are analysed quickly using the analytical model. The linear finite element analysis (FEA) is further applied to verify the analytical model for different joints. Given different geometrical parameters of the EAF sheet, their effects on the parasitic motion and the maximum deformation of the joint are elaborated. Nonlinear FEA is used to analyse nonlinearities of the joint consisting of straight sheets and a round wire beam, including the large deformation, load-dependent effect, and axial anti-buckling. Experimental results verify the accuracy of the derived analytical models and confirm the successful design of the proposed universal joint. [ABSTRACT FROM AUTHOR]