Abstract. Infrared images in the sky scence often contain different complexity noises, which affect the validity of target detection algorithm and result in high false alarm rate. In order to solve this problem, this paper proposes a method based on weighted order morphology, which utilizes the improved open operation to do the denoising and then uses the edge structuring element to extract the small target, and defines a weighted order morphology-based top-hat (WOTH) operation to suppress background while enhancing the target, and finally complete the detection of target by using a simple adaptive threshold. The algorithm combines three different structuring elements, and has four adjustable parameters. By controlling the structure elements' size and related parameters, the target and the background can be quickly separated, the use of weighted local entropy operation also enhance the target effectively. The experimental results show that the proposed algorithm can effectively suppress different types of interference and accurately detect infrared small targets, and has a good performance in robustness and fastness.
The ultrasonic welding was carried out to improve the quality of dissimilar Al/Mg alloys joint. The effects of laser texturing on the microstructure and mechanism of AZ31B/5052 joint connected by ultrasonic welding were also investigated. A series of laser texturing experiments on Al alloy (5052) and Mg alloy (AZ31B) were performed to determine the process parameters and their effect on ultrasonic weld quality, especially on weld strength. Little effect was attained by optimizing welding parameters in improving mechanical properties. Both welding parameters and different texture pattern were investigated to obtain good weld quality. The connection mechanisms of joints were discussed based on the analysis of weld interface morphology, microstructure evolution. Mechanical analysis of particle and movement of material atoms were analyzed in the study to explain the connect mechanism. The results show that the better lock-interface and lager lap shear strength were attained by laser texture addition and optimal welding parameters. Compared with the untextured joint, swirling bonding interface was obtained after the laser texture. The laser texture with grid pattern was found to raise the strength up to 26% higher maximum tensile-shear load than the joints obtained with the untextured surface.
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