Contemporary kinematic models and moment deficit of Chinese mainland

There are lots of achievements about kinematics of Chinese mainland and its vicinity determined from historic earthquake data, Quaternary fault rates and geodesy observations, which provide basic data for analysis of seismic hazard in study areas. Based on impreciseness in using energy of 47 earthquakes with magnitude greater than 7.0 in previous study, we firstly collected source parameters, surface ruptures and displacements of major earthquakes carefully, and divided them into small segmentations with these data gathered. Secondly, we determined contemporary deformation field from latest earthquake mechanisms, Quaternary fault slip rates and geodesy observations. Finally, we evaluated moment deficit of study areas from historic earthquake data and predicted deformation field, and removed 10 percent of aseismic deformation. Combining with previous results, we analyzed the seismic hazard of study areas. The results show that there are some areas with large moment deficit in Chinese mainland. There are also large moment deficit areas, including regions around the Ordos Block, southeastern coast of China and the Bakal rift zone. Previous studies show that there may be some potential earthquakes in the near future in Darts of areas mentioned above.

TFM imaging of aeroengine casing ring forgings with curved surfaces using acoustic field threshold segmentation and vector coherence factor

The aeroengine casing ring forgings have complex cross-section shapes,when the conventional ultrasonic or phased array is applied to detect such curved surfaces,the inspection images always have low resolution and even artifacts due to the distortion of the wave beam.In this article,taking a type of aeroengine casing ring forging as an example,the Total Focusing Method(TFM)algorithms for curved surfaces are investigated.First,the Acoustic Field Threshold Segmentation(AFTS)algorithm is proposed to reduce background noise and data calculation.Furthermore,the Vector Coherence Factor(VCF)is adopted to improve the lateral resolution of the TFM imaging.Finally,a series of 0.8 mm diameter Side-Drilled Holes(SDHs)are machined below convex and concave surfaces of the specimen.The quantitative comparison of the detection images using the conventional TFM,AFTS-TFM,VCF-TFM,and AFTS-VCF-TFM is implemented in terms of data volume,imaging Signal-to-Noise Ratio(SNR),and defect echo width.The results show that compared with conventional TFM,the data volume of AFTS-VCF-TFM algorithm for convex and concave is decreased by 32.39%and 73.40%,respectively.Moreover,the average SNR of the AFTS-VCF-TFM is gained up to 40.0 dB,while the average 6 dB-drop echo width of defects is reduced to 0.74 mm.