Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cyl...Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cylindrical shaped hyperlens can be used for super-resolution microwave focusing in a TE mode. Based on split ring resonators, the hyperlens satisfies a hyperbolic dispersion relationship. Simulations demonstrate that the focused spot size and position are insensitive to the rotation angle of the hyperlens around its geometric center. Experimental results show that a focused spot size 1/3 of the vacuum wavelength is achieved in the microwave band.展开更多
The general corrosion and local corrosion of Q235 steel were tested by acoustic emission （AE） detecting system under 6% FeCl3.6H2O solution to effectively detect the corrosion acoustic emission signal from complex b...The general corrosion and local corrosion of Q235 steel were tested by acoustic emission （AE） detecting system under 6% FeCl3.6H2O solution to effectively detect the corrosion acoustic emission signal from complex background noise. The short-time fractal dimension and discrete fractional cosine transform methods are combined to reduce noise. The input SNR is 0-15 dB while corrosion acoustic emission signals being added with white noise, color noise and pink noise respectively. The results show that the output signal-to-noise ratio is improved by up to 8 dB compared with discrete cosine transform and discrete fractional cosine transform. The above-mentioned noise reduction method is of significance for the identification of corrosion induced acoustic emission signals and the evaluation of the metal remaining life.展开更多
基金the National Natural Science Foundation of China under Grants Nos.11374235,61271150,61007024,and 10904118
文摘Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cylindrical shaped hyperlens can be used for super-resolution microwave focusing in a TE mode. Based on split ring resonators, the hyperlens satisfies a hyperbolic dispersion relationship. Simulations demonstrate that the focused spot size and position are insensitive to the rotation angle of the hyperlens around its geometric center. Experimental results show that a focused spot size 1/3 of the vacuum wavelength is achieved in the microwave band.
文摘The general corrosion and local corrosion of Q235 steel were tested by acoustic emission （AE） detecting system under 6% FeCl3.6H2O solution to effectively detect the corrosion acoustic emission signal from complex background noise. The short-time fractal dimension and discrete fractional cosine transform methods are combined to reduce noise. The input SNR is 0-15 dB while corrosion acoustic emission signals being added with white noise, color noise and pink noise respectively. The results show that the output signal-to-noise ratio is improved by up to 8 dB compared with discrete cosine transform and discrete fractional cosine transform. The above-mentioned noise reduction method is of significance for the identification of corrosion induced acoustic emission signals and the evaluation of the metal remaining life.
