Application of phased array ultrasonic technology for nondestructive testing of railway wheels
A scheme is proposed to realize nondestructive testing (NDT) of railway wheels based on phased array ultrasonic testing technology in order to ensure the safe operation and high-speed of railway transport, and achieve accurate determine the defects of railway wheels. A phased array ultrasonic NDT system for wheels was designed. The system includes four main parts: system management software, probe moving and scanning parts, ultrasonic signal acquisition and imaging. A testing scheme for wheels was designed aiming at the configuration of railroad wheels and the distribution of defects in them. The wheels safety testing experiments were carried out on model wheels with artificial defects. Results of experiments demonstrate that the testing methods are more accurate in examining the depth and the location of defects in the wheels, and this system can obtain the defects status of wheels with higher sensitivity, higher facilitation and less affection by environmental factors.
Ultrasonic Phased Array Industrial Imaging with Sub-Nyquist Sampling Rate
this paper uses a new type of FRI (Finite Rate of Innovation) sampling pattern based Sub-Nyquist sampling model breaked through Shannon theorem that it can get accurate signal reconstruction based on signal information rate, which requires the sampling frequency lower than two times the max signal frequency. We apply the new model in the ultrasonic phased array industrial imaging. In the experiment, ultrasonic phased array realized dynamic focusing and the high speed scan by ultrasonic array transducer of various array time delays to get flexible controllable synthesis beam composed signals that received by 32 phased array elements . The results indicate that in the model it greatly reduces the signal sampling frequency and improves the signal-to-noise ratio, frequency resolution at the same of the beam focusing and steering flexible.
Semiautomated quantification of the fibrous tissue response to complex three-dimensional filamentous scaffolds using digital image analysis.
Fibrosis represents a relevant response to the implantation of biomaterials, which occurs not only at the tissue-material interface (fibrotic encapsulation) but also within the void fraction of complex three-dimensional (3D) biomaterial constructions (fibrotic ingrowth). Usual evaluation of the biocompatibility mostly depicts fibrosis at the interface of the biomaterial using semiquantitative scores. Here, the relations between encapsulation and infiltrating fibrotic growth are poorly represented. Virtual pathology and digital image analysis provide new strategies to assess fibrosis in a more differentiated way. In this study, we adopted a method previously used to quantify fibrosis in visceral organs to the quantification of fibrosis to 3D biomaterials. In a proof-of-concept study, we transferred the "Collagen Proportionate Area" (CPA) analysis from hepatology to the field of biomaterials. As one task of an experimental animal study, we used CPA analysis to quantify the fibrotic ingrowth into a filamentous scaffold after subcutaneous implantation. We were able to demonstrate that the application of the CPA analysis is well suited as an additional fibrosis evaluation strategy for new biomaterial constructions. The CPA method can contribute to a better understanding of the fibrotic interactions between 3D scaffolds and the host tissue responses.