Detection and Imaging of Nonmetallic Inclusions in Continuously Cast Steel Plates by Higher Harmonics

Abstract

We study the level spacing distribution p(s) in the spectrum of random networks. According to our numerical results, the shape of p(s) in the Erdős-Rényi (E-R) random graph is determined by the average degree k and p(s) undergoes a dramatic change when k is varied around the critical point of the percolation transition, k = 1. When k 1, the p(s) is described by the statistics of the Gaussian orthogonal ensemble (GOE), one of the major statistical ensembles in Random Matrix Theory, whereas at k = 1 it follows the Poisson level spacing distribution. Closely above the critical point, p(s) can be described in terms of an intermediate distribution between Poisson and the GOE, the Brodydistribution. Furthermore, below the critical point p(s) can be given with the help of the regularized Gamma-function. Motivated by these results, we analyse the behaviour of p(s) in real networks such as the internet, a word association network and a protein-protein interaction network as well. When the giant component of these networks is destroyed in a node deletion process simulating the networks subjected to intentional attack, their level spacing distribution undergoes a similar transition to that of the E-R graph.

Research on Residual Life Estimation Method for KMN Steel Based on Nonlinear Ultrasonic Testing

“…In 1998, Nagy et al [12] used nonlinear ultrasonic tests to evaluate the performance degradation of materials from cracks to fractures and predict the fatigue life of the materials. In 2010, Kawashima [13] used a nonlinear scanning system to detect non-metallic inclusions in continuum cast steel. In 2011, Viswanath [14] found that nonlinear coefficients can be used to characterize the degradation of mechanical properties of materials under tensile loads.…”

Research on Fatigue Damage of Compressor Blade Steel KMN-I Using Nonlinear Ultrasonic Testing

“…In 1999, Jhang and Kim [7] researched the relationship between the mechanical properties degradation of the material and the nonlinearity parameter under tensile load. In 2010, Kawashima et al [8] detected the nonmetallic inclusions in the continuous casting steels using a nonlinear scanning system. In 2012, Cremer et al [9] carried out the in situ observation of the very high cycle fatigue damage evolution of aluminum alloy welded joints using nonlinear ultrasonic technology.…”

Application of ultrasonic computerized tomography using time-of-flight measured by transmission method to nondestructive inspection for high-attenuation billets

“…Ultrasound waves attenuate inside a metal because of diffusion and grain boundary scattering. [14][15][16][17] Although the pulse echo method is useful for forge steel, which is comparatively low-attenuation steel, it is not effective for high-attenuation steel such as cast steel. 18) Therefore, an ultrasonic transmission method is expected to detect defects inside high-attenuation billets.…”