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The force mechanism and progressive collapse of steel tube-coupler scaffolds were studied under a local load. A distributed optical fiber system was used to conduct experiments on four different scaffold erections. The stresses of the vertical rods, horizontal rods and braces had ladder-like distributions; braces sustained most of the axial force, whereas vertical and horizontal rods sustained an axial force and bending moment. A reasonable numerical analysis strategy is established on the basis of this research and a comparison with experiments, and the progressive collapse process is simulated using ANSYS software. Horizontal rods and braces not only provide auxiliary support for the vertical rods, but also contribute to forces throughout the scaffold; internal forces pass through the two types of bar and are redistributed in each vertical rod such that all vertical rods are associated with forces in the scaffold. Braces block the spread of local collapse within the same floor while bottom horizontal rods block that from one floor to another. The addition of braces and bottom horizontal rods can therefore effectively prevent progressive collapse.

In this paper, we propose a novel quality assessment of finger-vein images for quality control in the enrollment and authentication of a finger-vein verification system. First, a Radon transform based model is employed to assess the quality of a finger-vein grayscale image. Second, to assess the quality of a finger-vein binary image, we further proposed three evaluation functions to measure the connectivity, smoothness and reliability of the binary version of the finger-vein image. Finally, the scores from the finer-vein binary images are fused with these from finger-vein grayscale images to improve the performance. Experimental results show that our approach can effectively identify the low quality finger-vein images, which is also helpful in improving the performance of the finger-vein verification system. We also show that instead of choosing the images with the highest quality as the enrollment templates, using the templates with the mid-range quality would achieve better performance with respect to improvement of varication accuracy.

Terfenol is an ideal choice for medium to high power low frequency sonar. It can offer the transducer designer higher strain, higher power density, but the designer must be aware of the eddy current. To enhance efficiency of the barrel-stave transducer powered by a Terfenol rod, radial slots rather than laminations were used to control eddy currents in the Terfenol drive rod, and the effectiveness and the number of these slots were studied experimentally and calculated by finite element modeling. Based on the characteristic of vortex path,a new simple geometrical method to calculate the number of the radial slots of a Terfenol rod at the operating frequency is put forward in this paper. Moreover, the calculated results are in good agreement with those of using the finite element method (FEM) for the slotted Terfenol rod given by the literature. The method will save much cost to design Terfenol rod transducers.