Localized corrosion of aluminum(Al)alloys,such as pitting corrosion,intergranular corrosion,and stress corrosion cracking is closely related to the micro-galvanic corrosion between the second phase and the Al matrix.U...Localized corrosion of aluminum(Al)alloys,such as pitting corrosion,intergranular corrosion,and stress corrosion cracking is closely related to the micro-galvanic corrosion between the second phase and the Al matrix.Using high-resolution transmission electron microscopy and first principles calculations,the factors that affect corrosion mechanisms of the second phase in Al alloys at micro-scale and atomic-scale were examined,including the composition and structure of second phase,pH of the environment,stress and adsorption behavior of adsorbates(such as Cl^(−),H_(2)O,OH−and O_(2)^(−).展开更多
Ocean fishing is one of the most important parts of the fishery economy in China. After more than 20 years of development, China has developed into one of the major ocean fishing countries in the world. However, due t...Ocean fishing is one of the most important parts of the fishery economy in China. After more than 20 years of development, China has developed into one of the major ocean fishing countries in the world. However, due to the influence of natural laws at home and abroad, China＇s deep-sea fisheries have been faced with difficulties such as rising costs, increasing competition pressure on fishery resources and backward fishery equipment. In recent years, the development of ocean fishing has faced many difficulties. Therefore, this paper analyzes the economic and social benefits of the steel ocean fishing vessel and the glass and steel ocean fishing vessel. It has reached the aim of providing theoretical support for the new development direction of ocean fishing in China. Among them, the economic benefits are mainly compared and analyzed from four aspects of the maintenance fee, depreciation, fuel consumption and operational efficiency. Social benefits are mainly embodied in the aspects of energy saving, emission reduction, increasing consumption and reducing consumption, protecting resources and environment, ensuring the safety of fishermen at sea, optimizing the structure of fishery industry, and promoting standardization of fishing vessels. Through the analysis of these two aspects, the advantage and the obvious gain effect of the FRP ocean fishing vessel are fully proved. The FRP ocean fishing vessels can be realized more quickly by the enterprises built and used. Finally, it can promote the development of ocean FRP Ocean fishing vessels in China.展开更多
For the detection of underwater target echo under strong interferences,the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature,and the rela...For the detection of underwater target echo under strong interferences,the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature,and the relationship between signal spectral irregularity and target physical properties is theoretically formed.A novel method of broadband underwater target echo detection under reverberation based on the signal spectral irregularity characteristics is proposed.The proposed method has the capability of discriminating between the direct target echo signal from reverberation.Simulation results of complex underwater target broadband acoustic scattering show that the echo can be detected even with the signal to reverberation ratio(SRR)below-10 dB by the proposed method based on the spectral irregularity(SI)feature.The corresponding sea experimental results also show that echo can be detected when the SRR is below 0 dB.The effectiveness and correctness of the proposed method are verified both in simulated data and in real data in sea experiment.展开更多
基金financial support from the National Natural Science Foundation of China (No. 52171077)。
文摘Localized corrosion of aluminum(Al)alloys,such as pitting corrosion,intergranular corrosion,and stress corrosion cracking is closely related to the micro-galvanic corrosion between the second phase and the Al matrix.Using high-resolution transmission electron microscopy and first principles calculations,the factors that affect corrosion mechanisms of the second phase in Al alloys at micro-scale and atomic-scale were examined,including the composition and structure of second phase,pH of the environment,stress and adsorption behavior of adsorbates(such as Cl^(−),H_(2)O,OH−and O_(2)^(−).
文摘Ocean fishing is one of the most important parts of the fishery economy in China. After more than 20 years of development, China has developed into one of the major ocean fishing countries in the world. However, due to the influence of natural laws at home and abroad, China＇s deep-sea fisheries have been faced with difficulties such as rising costs, increasing competition pressure on fishery resources and backward fishery equipment. In recent years, the development of ocean fishing has faced many difficulties. Therefore, this paper analyzes the economic and social benefits of the steel ocean fishing vessel and the glass and steel ocean fishing vessel. It has reached the aim of providing theoretical support for the new development direction of ocean fishing in China. Among them, the economic benefits are mainly compared and analyzed from four aspects of the maintenance fee, depreciation, fuel consumption and operational efficiency. Social benefits are mainly embodied in the aspects of energy saving, emission reduction, increasing consumption and reducing consumption, protecting resources and environment, ensuring the safety of fishermen at sea, optimizing the structure of fishery industry, and promoting standardization of fishing vessels. Through the analysis of these two aspects, the advantage and the obvious gain effect of the FRP ocean fishing vessel are fully proved. The FRP ocean fishing vessels can be realized more quickly by the enterprises built and used. Finally, it can promote the development of ocean FRP Ocean fishing vessels in China.
基金The 13th Five-Year Plan for Advanced Research Program(No.41416030301)
文摘For the detection of underwater target echo under strong interferences,the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature,and the relationship between signal spectral irregularity and target physical properties is theoretically formed.A novel method of broadband underwater target echo detection under reverberation based on the signal spectral irregularity characteristics is proposed.The proposed method has the capability of discriminating between the direct target echo signal from reverberation.Simulation results of complex underwater target broadband acoustic scattering show that the echo can be detected even with the signal to reverberation ratio(SRR)below-10 dB by the proposed method based on the spectral irregularity(SI)feature.The corresponding sea experimental results also show that echo can be detected when the SRR is below 0 dB.The effectiveness and correctness of the proposed method are verified both in simulated data and in real data in sea experiment.
