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This paper addresses the problem of high-resolution imaging of shadowed multiple-targets with limited labeled data, by proposing a transfer-learning-based method for through-the-wall radar imaging. First, a generative adversarial sub-network is developed to facilitate the migration of labeled simulation data to measured data, overcoming the difficulty of generating labeled data. This method incorporates an attention mechanism, adaptive residual blocks, and a multi-scale discriminator to improve the quality of image migration. It also incorporates a structural consistency loss function to minimize perceptual differences between images. Finally, the labeled data are used to train the through-the-wall radar target-imaging sub-network, achieving high-resolution imaging of multiple targets through walls. Experimental results show that the proposed method effectively reduces discrepancies between simulated and obtained images, and generates pseudo-measured images with labels. It systematically addresses issues such as side/grating ghost interference, target image defocusing, and multi-target mutual interference, significantly improving the multi-target imaging quality of the through-the-wall radar. The imaging accuracy achieved is 98.24%, 90.97% and 55.17% for single, double, and triple-target scenarios, respectively. Compared with CycleGAN, the imaging accuracy for the corresponding scenarios is improved by 2.29%, 40.28% and 15.51%, respectively.

The application of the cast WC, the Co powder coated cast WC and the Ni powder coated cast WC particles in diamond saw blades were studied, and their effects on the mechanical properties, the micro morphologies and the cutting properties of the diamond saw blade matrix were explored. The results show that when the mass ratio of the three kinds of WC material to the metal powder is 3∶1, the hardness of the three kinds of matrix is equivalent. The bending strength of the matrix containing Co powder coated cast WC is the highest, the interface between the WC particles and the matrix is the closest, and the microstructure of the matrix is the densest. The bending strength of the matrix containing Ni powder coated cast WC is the second. The matrix with only cast WC has the worst bending strength. Compared with the saw blade with only cast WC added, the cutting life of the saw blade with Co powder coated cast WC is the longest and increases by 40%.

In this paper, the “sonar percolation detection or logging” technology, which has emerged recently, is questioned from the aspects of test principle and calculation method, and the serious problems of this technology are pointed out. It is considered that sonar technology can not be used for seepage testing.