Coded excitation technology （CET） can effectively enhance the penetration and resolution of ultrasonic testing. To analyze the influence of rock properties on pulse compression performance （PCP） of coded excitatio...Coded excitation technology （CET） can effectively enhance the penetration and resolution of ultrasonic testing. To analyze the influence of rock properties on pulse compression performance （PCP） of coded excitation signals （CES）, a numerical simulation, and an ultrasonic experiment on different rock samples are performed; and the detection ability of several CESs are also investigated and compared. The results of experiments showed that the loss of the signal-to-noise ratio （SNR） of Barker coded signal with tapered linear frequency modulated carrier （BTLFM） is always less than Barker coded signal with sine carrier （BS）, while the resolution loss of BTLFM is lower than tapered linear frequency modulated signal （TLFM）. In sum, the results not only verifiy the effectiveness of CET, but also provide a basis for the parameter settings of coded signals used in rock ultrasonic testing.展开更多
Foxtail millet （Setaria italica） is one of the most valuable species in economic terms in the genus Setaria and plays an important role in human nutrition, animal feed, and agriculture. The present study described c...Foxtail millet （Setaria italica） is one of the most valuable species in economic terms in the genus Setaria and plays an important role in human nutrition, animal feed, and agriculture. The present study described chemical, physical, and quality aspects of seeds of foxtail millet. Furthermore, the fluid-dynamic behavior of the seeds was evaluated in a conical spouted bed, which has advantages in terms of promoting the cyclic and regular movement of the seed particles. Dynamic parameters of spouting （minimum spouting veloc- ity, stable and peak pressure drop） were determined and compared with those obtained from empirical correlations available in the literature. The results obtained from physical characterization showed that the seeds can be classified as belonging to Group D of Geldart, having a non-rough surface, mean diameter of 1.75 mm, and sphericity of 0.74. Fluid-dynamics analysis showed that the seeds are suitable for processing in a spouted bed, which is in agreement with the results of particle physical characterization.展开更多
A decomposition approach of the combinational functions is discussed. A design method, by which the minimization or near minimization of two-level combinational network can be obtained, is presented for a combinationa...A decomposition approach of the combinational functions is discussed. A design method, by which the minimization or near minimization of two-level combinational network can be obtained, is presented for a combinational function realized by using multiplexer universal logic modules. Using the method, the automated synthesis of the combinational functions can be accomplished on a computer.展开更多
基金supported by the National Natural Science Foundation of China(41104117)
文摘Coded excitation technology （CET） can effectively enhance the penetration and resolution of ultrasonic testing. To analyze the influence of rock properties on pulse compression performance （PCP） of coded excitation signals （CES）, a numerical simulation, and an ultrasonic experiment on different rock samples are performed; and the detection ability of several CESs are also investigated and compared. The results of experiments showed that the loss of the signal-to-noise ratio （SNR） of Barker coded signal with tapered linear frequency modulated carrier （BTLFM） is always less than Barker coded signal with sine carrier （BS）, while the resolution loss of BTLFM is lower than tapered linear frequency modulated signal （TLFM）. In sum, the results not only verifiy the effectiveness of CET, but also provide a basis for the parameter settings of coded signals used in rock ultrasonic testing.
文摘Foxtail millet （Setaria italica） is one of the most valuable species in economic terms in the genus Setaria and plays an important role in human nutrition, animal feed, and agriculture. The present study described chemical, physical, and quality aspects of seeds of foxtail millet. Furthermore, the fluid-dynamic behavior of the seeds was evaluated in a conical spouted bed, which has advantages in terms of promoting the cyclic and regular movement of the seed particles. Dynamic parameters of spouting （minimum spouting veloc- ity, stable and peak pressure drop） were determined and compared with those obtained from empirical correlations available in the literature. The results obtained from physical characterization showed that the seeds can be classified as belonging to Group D of Geldart, having a non-rough surface, mean diameter of 1.75 mm, and sphericity of 0.74. Fluid-dynamics analysis showed that the seeds are suitable for processing in a spouted bed, which is in agreement with the results of particle physical characterization.
文摘A decomposition approach of the combinational functions is discussed. A design method, by which the minimization or near minimization of two-level combinational network can be obtained, is presented for a combinational function realized by using multiplexer universal logic modules. Using the method, the automated synthesis of the combinational functions can be accomplished on a computer.
