A mechanical model of the quasi-static interface of a mode I crack between a rigid and a pressure-sensitive viscoelastic material was established to investigate the mechanical characteristic of ship-building engineeri...A mechanical model of the quasi-static interface of a mode I crack between a rigid and a pressure-sensitive viscoelastic material was established to investigate the mechanical characteristic of ship-building engineering hi-materials. In the stable growth stage, stress and strain have the same singularity, ie （σ, ε） ∝ r^-1/（n-1）. The variable-separable asymptotic solutions of stress and strain at the crack tip were obtained by adopting Airy＇s stress function and the numerical results of stress and strain in the crack-tip field were obtained by the shooting method. The results showed that the near-tip fields are mainly governed by the power-hardening exponent n and the Poisson ratio v of the pressure-sensitive material. The fracture criterion of mode I quasi-static crack growth in pressure-sensitive materials, according to the asymptotic analyses of the crack-tip field, can be viewed from the perspective of strain.展开更多
A metamaterial was introduced into the cover of a patch antenna and its band structure was analyzed. The metama- terial cover with correct selection of the working frequency increases by 9.14 dB the patch antenna’s d...A metamaterial was introduced into the cover of a patch antenna and its band structure was analyzed. The metama- terial cover with correct selection of the working frequency increases by 9.14 dB the patch antenna’s directivity. The mechanism of metamaterial cover is completely different from that of a photonic bandgap cover. The mechanism of the metamaterial cover, the number of the cover’s layers, and the distance between the layers, were analyzed in detail. The results showed that the metamaterial cover, which works like a lens, could effectively improve the patch antenna’s directivity. The physical reasons for the improvement are also given.展开更多
Cardanol polyoxyethylene ether is a kind of nonionic surfactants based on natural raw materials, with good surface activity and resistance to hard water. At 25 ℃, the value of critical micelle concentration （CMC） i...Cardanol polyoxyethylene ether is a kind of nonionic surfactants based on natural raw materials, with good surface activity and resistance to hard water. At 25 ℃, the value of critical micelle concentration （CMC） is 6.09×10-6 mol/L, and the lowest surface tension （TcMc） is 38.08 mN/m. Moreover, cardanol polyoxyethylene ether has strong salt tolerance to monovalent inorganic salts; with the increase of concentration of divalent inorganic salt, the surface activity of cardanol polyoxyethylene ether is enhanced. The effect of monohydric alcohol on the surface activity of cardanol polyoxyethylene ether is complex： the ability of BGF-10 to form micelles increases and then decreases with the increase of the concentration of monohydric alcohol, cardanol polyoxyethylene ether has a synergistic effect with anionic, nonionic and cationic surfactants, especially with hexadecyltrimethylammonium bromide （CTAB）, and its critical micelle concentration is decreased by 2.52%, while the surface tension is decreased by 11.49%. Test results also show, comparing to nonylphenol polyoxyethylene ether, the emulsifying and the thickening performances of cardanol polyoxyethylene ether are better, and its foam performance is lower. Also, the cloud point of cardanol polyoxyethylene ether is higher than nonylphenol polyoxyethylene ether. In most case, the detergency of cardanol polyoxyethylene ether is better than or equivalent to nonylphenol polyoxyethylene ether. cardanol polyoxyethylene ether is an excellent alternative to nonylphenol polyoxyethylene ether in detergents.展开更多
基金Supported by Heilongjiang Province Foundation under Grant No.LC08C02
文摘A mechanical model of the quasi-static interface of a mode I crack between a rigid and a pressure-sensitive viscoelastic material was established to investigate the mechanical characteristic of ship-building engineering hi-materials. In the stable growth stage, stress and strain have the same singularity, ie （σ, ε） ∝ r^-1/（n-1）. The variable-separable asymptotic solutions of stress and strain at the crack tip were obtained by adopting Airy＇s stress function and the numerical results of stress and strain in the crack-tip field were obtained by the shooting method. The results showed that the near-tip fields are mainly governed by the power-hardening exponent n and the Poisson ratio v of the pressure-sensitive material. The fracture criterion of mode I quasi-static crack growth in pressure-sensitive materials, according to the asymptotic analyses of the crack-tip field, can be viewed from the perspective of strain.
基金Project (No. 2004CB719802) supported by the National Basic Research Program (973) of China
文摘A metamaterial was introduced into the cover of a patch antenna and its band structure was analyzed. The metama- terial cover with correct selection of the working frequency increases by 9.14 dB the patch antenna’s directivity. The mechanism of metamaterial cover is completely different from that of a photonic bandgap cover. The mechanism of the metamaterial cover, the number of the cover’s layers, and the distance between the layers, were analyzed in detail. The results showed that the metamaterial cover, which works like a lens, could effectively improve the patch antenna’s directivity. The physical reasons for the improvement are also given.
文摘Cardanol polyoxyethylene ether is a kind of nonionic surfactants based on natural raw materials, with good surface activity and resistance to hard water. At 25 ℃, the value of critical micelle concentration （CMC） is 6.09×10-6 mol/L, and the lowest surface tension （TcMc） is 38.08 mN/m. Moreover, cardanol polyoxyethylene ether has strong salt tolerance to monovalent inorganic salts; with the increase of concentration of divalent inorganic salt, the surface activity of cardanol polyoxyethylene ether is enhanced. The effect of monohydric alcohol on the surface activity of cardanol polyoxyethylene ether is complex： the ability of BGF-10 to form micelles increases and then decreases with the increase of the concentration of monohydric alcohol, cardanol polyoxyethylene ether has a synergistic effect with anionic, nonionic and cationic surfactants, especially with hexadecyltrimethylammonium bromide （CTAB）, and its critical micelle concentration is decreased by 2.52%, while the surface tension is decreased by 11.49%. Test results also show, comparing to nonylphenol polyoxyethylene ether, the emulsifying and the thickening performances of cardanol polyoxyethylene ether are better, and its foam performance is lower. Also, the cloud point of cardanol polyoxyethylene ether is higher than nonylphenol polyoxyethylene ether. In most case, the detergency of cardanol polyoxyethylene ether is better than or equivalent to nonylphenol polyoxyethylene ether. cardanol polyoxyethylene ether is an excellent alternative to nonylphenol polyoxyethylene ether in detergents.
