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As an important link to ensure the welding quality, the post-welding inspection of resistance spot welding joints has been paid much attention in the welding production of stainless steel metro vehicle body. At present, ultrasonic testing technology for spot welding joint quality is mostly qualitative testing, which cannot determine the quality information such as the geometric state of nugget and the size of internal defects. Therefore, the research on ultrasonic propagation characteristics and sound field distribution in resistance spot welding joints is carried out, and the visual image of internal connection state of spot welding joints is the key to realize quantitative nondestructive testing and quality evaluation of spot welding joints, which has important theoretical significance and practical value, and has broad application prospects in technical fields such as automobiles, rail passenger cars, aerospace and machinery.

The rapid growth of emerging technologies with artificial intelligence and big data as new representatives has brought great influence to all walks of life, as well as the education. College sports is an important part of the education system and deeply affected by the artificial intelligence. The paper will briefly summarize the current status of college physical education in China and discuss how to innovate its methods in the era of artificial intelligence.

An alarming settlement has been observed during the operation of transport infrastructures built on soft clay areas. Considering the long duration of traffic load, analyzing the long-term cyclic behavior of saturated soft clay considering different drainage conditions is of considerable significance. In this study, a series of cyclic triaxial tests were conducted on undisturbed soft clay from Wenzhou under the partially drained and undrained conditions, respectively. The test results reveal that: (a) more permanent strain was generated of the soft clay specimen under partially drainage condition, which is due to the volume change caused by both the decrease of void ratio and the shape deformation of specimens; (b) under partially drained condition, the resilient strain and hysteretic loops both exhibit a sudden increase in strain due to transient softening induced by excess pore water generated in the early stage followed by a reduction until a steady value is attained; (c) it is obvious that the allowable cyclic stress ratio (CSR) under undrained condition is larger than that under partially drained condition, indicating that considering partially drained condition is necessary in practical engineering design.

Background Tumor invasion or adherence to the portal vein–superior mesenteric vein (PV/SMV) may be encountered during pancreatic surgery. In such cases, venous resection and reconstruction might be required for complete resection of the tumor. We report an innovative technique in which the graft for PV/SMV reconstruction was made with the falciform ligament. Methods Between May 2011 and July 2016, PV/SMV reconstruction with a falciform ligament graft was performed in 10 cases during pancreatectomy. Among these cases, including six cases with a patch graft and four cases with a conduit graft. Retrospective reviews of medical records and radiologic studies were performed. Results Ten patients with pancreatobiliary cancer underwent en bloc tumor resection with concurrent PV/SMV resection and reconstruction with a falciform ligament graft. There were six males and four females, and the mean age was 65.3 ± 9.4 (48-80) y. Using Doppler ultrasound examination, all 10 grafts were shown to be patent at postoperative 2 wk. However, occlusion was found in one case with conduit graft and stenosis in the other three cases with conduit graft using enhanced computed tomography at postoperative 2 mo. Complete patency was shown in three of six cases with patch graft and stenosis in the other three cases at 2 mo after the operation. Although occlusion or stenosis of the grafts was observed, no severe adverse events occurred, and normal liver function was discovered in all 10 cases at postoperative 2 mo. Conclusions Falciform ligament grafts might be considered for reconstruction of PV/SMV in the absence of appropriate vascular grafts.

Combination of liquid hot water pretreatment (LHWP) and wet disk milling (WDM) was investigated in this study to enhance the sugar recovery yield both in prehydrolyzate and enzymatic hydrolyzate. The results show that WDM with LHWP at 180 °C for 20 min produced maximum xylose and glucose yields of 91.62% and 88.12%, respectively, which are higher than that of dilute acid pretreatment or individual LHWP. Corresponding concentration of fermentation inhibitors such as acetic acid, HMF, and furfural in the prehydrolyzate are about 0.98, 0.07 and 0.78 g/L, respectively, which indicated that the detoxification may be not required in the next fermentation step. The acid-insoluble lignin recovery in the insoluble solid resulting from enzymatic hydrolysis, was 25.67/100 g raw material, representing 90.7% of acid-insoluble lignin in the eucalyptus biomass. It can be concluded that liquid hot water pretreatment combined with wet disk milling can be successfully applied to eucalyptus.