The variation, with material parameters, of Lamb modes is investigated. Vibration spectra of traction-free elastic plates are generally presented, for a given isotropic material, as a set of dispersion curves corresponding to the various Lamb mode branches. Here, the spectrum variations, with the Poisson ratio nu, are plotted in a dimensionless co-ordinate system in the form of a bundle of curv...

In this study, the effect of cortical thickness variation on the propagation of leaky Lamb waves is investigated by using an axial transmission technique commonly used to characterize long bones. Three Lucite plates with thicknesses of 1, 3, and 5 mm as bone phantoms and one bovine tibia with a cortical thickness of 2 mm were used at various low frequencies. Experimental measurements in bone ph...

Wave scattering analysis implemented by boundary element methods (BEM) and the normal mode expansion technique is used to study the sizing potential of two-dimensional shaped defects in a wave guide. Surface breaking halfelliptical shaped defects of three opening lengths (0.3, 6.35 and 12.7 mm) and through-wall depths of 10–90% on a 10 mm thick steel plate were considered. The reflection and tr...

Lamb waves have been reported to be an efficient tool for non-destructive evaluations (NDE) for various application scenarios. However, accurate and reliable damage quantification using the Lamb wave method is still a practical challenge, due to the complex underlying mechanism of Lamb wave propagation and damage detection. This paper presents a Lamb wave damage quantification method using a le...

Recent analyses of the composition of South African lamb have yielded more positive findings than those reported previously. Evidently the fat content is much less than previously reported, and more appropriate according to recommendations set for the prevention of cardiovascular disease. The protein content and the vitamin constituents are proposed to be conducive to the metabolism of methioni...

number of NDE applications. To excite Lamb waves, Ultrasonic Lamb wave techniques are widely used in a mode conversion of bulk waves or photo acoustic excitation are often used. Both of these approaches suffer from the need for liquid couplant or ablation of materials to reach good signal to noise ratio. In this paper, we propose a novel technique that utilizes point source excitation and detec...

This paper proposes a novel Lamb wave line sensing technique for crack detection in a welded stiffener. The proposed technique overcomes one of the biggest technical challenges of Lamb wave crack detection for real structure applications: crack-induced Lamb waves are often mixed with multiple reflections from complex waveguides. In particular, crack detection in a welded joint, one of the struc...

Advanced techniques for observing protein localization in live bacteria show that the distributions are dynamic. For technical reasons, most such techniques have not been applied to outer membrane proteins in Gram-negative bacteria. We have developed two novel live-cell imaging techniques to observe the surface distribution of LamB, an abundant integral outer membrane protein in Escherichia col...

Scrapie is one of several transmissible spongiform encephalopathies of livestock. Disease susceptibility is linked to polymorphisms in the normal prion protein gene that encodes the mammalian prion precursor. Codon 171 of this gene is a major determinant of scrapie susceptibility. Selection for arginine (R) at codon 171 is encouraged by the USDA to decrease the incidence of scrapie. Objectives ...

twenty-four 35-day-old lambs were distributed to a completely randomized design with 3 treatments to study the effects of number of feeding buckets per pen on performance, haematology and behaviour indicators. treatments consisted of 8 (t1), 4 (t2) or 2 (t3) feeding buckets/pen (8 lambs/pen). during the experiment, concentrate was fed at 08:30 in individual feeders. daily dry matter intake (dmi...