Prodders are widely used devices in landmine detection. A sensorized prodder has been developed to detect shallow buried landmines by their vibrational characteristics. However, the influencing mechanisms of prodder’s components on the measured vibrational characteristics are not clear, and the vibration intensity of the buried landmine decreases with burial depth. A numerical analysis method is proposed to investigate the effects of parameters of prodder-object coupling system on the measured vibrational characteristics. The calculated main resonance frequency is 109.2 Hz, which corresponds well with the published analogy result of 110 Hz, and the mathematical method is also validated by the previous experimental results. Based on the proposed analysis method, an optimized prodder is designed, whereby the signal strength can theoretically increase 122.78%, which means that a greater depth of detection can be acquired. This optimal design is verified by the simulation experiment that was conducted with the optimization function of Adams software.
Background:
The solidification of metals is usually initiated by heterogeneous nucleation, which, however, is less controllable due to the unexpected impurities. In this study, the nucleation behavior of micro- and nano-sized Bi droplets embedded in the Cu matrix, where well-identified catalyst interfaces were introduced, was studied.
Objective:
This paper demonstrated the nucleation behavior of the nano-sized Bi droplets embedded in the Cu matrix to determine the nucleation sites and contact angle.
Methods:
Cu-20Bi (wt. %) melt-spun ribbons consisting of numerous micro- and nano-sized Bi droplets embedded in the Cu matrix were prepared. Based on the structure characterization by transmission electron microscopy (TEM), the nucleation behavior of these embedded Bi droplets was demonstrated by nanocalorimetry.
Results:
The orientation relationship between the nano-sized Bi droplets and the Cu matrix was determined. The undercooling of the nano-sized Bi droplets with cooling rate was more stable than that of the micro-sized Bi droplets, and a nucleation contact angle of 72o was obtained.
Conclusion:
The undercooling increases with the reduction of droplet size. The nucleation of the Bi droplets is significantly affected by their interfacial structure with the Cu matrix. Compared with hexagonal Zn, the Cu matrix with face-centered cubic structure has a less catalytic effect on the nucleation of Bi.
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