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The aim of this study was to investigate the effectiveness of restoration of gold foils on Dazu Grottoes using different parylene coatings.

The gold foil samples were applied with two types of parylene coating with six different thicknesses, C‐10, C‐15, C‐20, N‐10, N‐20, N‐25, respectively. Electrochemical impedance, surface morphology, and hydrophobicity properties were used to examine the behavior of the coatings.

The results showed that an increase in electrochemical corrosion resistance was observed as the degree of coating thickness was increased for both C‐parylene and N‐parylene coatings. In addition, the surface morphology study, using 3D topography measurement, indicated that the surface roughness was decreased for all parylene coatings. Furthermore, the parylene‐C coating was comparatively more effective than was the parylene‐N coating.

The results obtained from the three methods were in close agreement. This is an indication that the parylene‐C coating can be used to restore the gold foils on Dazu Grottoes and to support future restoration and consolidation to be applied on site on the Grottoes.

Because of the small size and high integration of capacitive micromachined ultrasonic transducer (CMUT) component, it can be made into large-scale array, but this lead to high hardware complexity, so the purpose of this paper is to use less elements to achieve better imaging results. In this research, an optimized sparse array is studied, which can suppress the side lobe and reduce the imaging artifacts compared with the equispaced sparse array with the same number of elements.

Genetic algorithm is used to sparse the CMUT linear array, and Kaiser window apodization is added to reduce imaging artifacts, the beam pattern and peak-to-side lobe ratio are calculated, point targets imaging comparisons are performed. Furthermore, a 256-elements CMUT linear array is used to carry out the imaging experiment of embedded mass and forearm blood vessel, and the imaging results are compared quantitatively.

Through the imaging comparison of embedded mass and forearm blood vessel, the feasibility of optimized sparse array of CMUT is verified, and the purpose of reducing the hardware complexity is achieved.

This research provides a basis for the large-scale CMUT array to reduce the hardware complexity and the amount of calculation. At present, the CMUT array has been used in medical ultrasound imaging and has huge market potential.