As a three-dimensional layer enhancement technology, the Z-pin technology is suitable for manufacturing composite prepreg laminates and can also effectively improve their interlaminar properties. In order to manufactu...As a three-dimensional layer enhancement technology, the Z-pin technology is suitable for manufacturing composite prepreg laminates and can also effectively improve their interlaminar properties. In order to manufacture Z-pin composite parts efficiently, this paper proposes a transi- tional insertion system, and according to the technical requirements of the transitional insertion process and the functional requirements of the transitional insertion platform, proposes a transition insertion plan which can insert multiple Z-pins into a carrier. A prototype machine has been designed and made, and a series of function debugging and verification experiments have been car- ried out on the machine. Some problems show up during the experiments, but based on the analysis of the reasons, this paper provides lots of solutions, and finally demonstrates the feasibility and practical value of the system. The results show that the system meets all technical requirements of the Z-pin insertion process. It is capable to insert multiple Z-pins into a foam carrier; as a result, the system is as much as 5 times more efficient than existing equipment, and the deviation for the insertion distance can be controlled within 0.3 mm. This Z-pin transitional insertion platform pro- motes the use of Z-pins in national defense and lays the foundation for commercializing the Z-pin technology.展开更多
A backward wave amplifier（BWA） in a terahertz regime with a novel slow-wave structure（SWS） composed of multi parallel grating pins inside a rectangular waveguide is analyzed. The multi-pin rectangular waveguide SW...A backward wave amplifier（BWA） in a terahertz regime with a novel slow-wave structure（SWS） composed of multi parallel grating pins inside a rectangular waveguide is analyzed. The multi-pin rectangular waveguide SWS possesses good performance and is compatible with micro-fabrication technologies. The dispersion and interaction impedance of the multipin SWS are presented. The stopbands of the modes cling together in a Brillouim zone. The SWS has a high interaction impedance that is suitable for the interaction of multi cylindrical beams. The design, which is based on three parallel pins supporting the wave–beam interaction with four cylindrical beams, is verified by three-dimensional particle-in-cell simulations. A BWA with the central frequency at 340 GHz is demonstrated, and the output power is more than 100 mW.A tuning frequency range of 15 GHz（333–348 GHz） is obtained with a gain of more than 20 dB.展开更多
Removal of single component and binary mixtures of benzene and m-xylene using a multi-pin-mesh reactor was studied to find the decomposition characteristics, carbon balance and CO2 selectivity. The decomposition rate ...Removal of single component and binary mixtures of benzene and m-xylene using a multi-pin-mesh reactor was studied to find the decomposition characteristics, carbon balance and CO2 selectivity. The decomposition rate of benzene in mixture was approximately 16% lower than that of single component benzene. However, the decomposition rate of m-xylene in mixture was slightly higher than that of single component m-xylene. Carbon balance of the mixture decomposition process achieved a lower level than that of single component benzene/m-xylene. Increase in the specific input energy was helpful to improve CO2 selectivity in the single component decomposition process, while the specific input energy had a negligible effect on CO2 selectivity in the mixture decomposition process. By changing the oxygen content in background gas, we found that different types of radicals showed different reaction activities toward benzene and m-xylene. Benzene was more likely to react with nitrogen-containing radicals, while m-xylene was more likely to react with oxygen-containing radicals.展开更多
小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失...小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失效。本研究以SOP和BGA元件为研究对象,提出一种结合图像融合差分、缺陷连通域标记和基于倾斜前后引脚外边缘中心点距离变化比对方法的多级引脚缺陷检测方法,以实现元件引脚缺陷的准确检测。实验结果表明,矩形引脚元件SOP和球形引脚元件BGA的总体检测准确率达到了95%以上,且缺陷检测的整体平均耗时均在100ms以内,满足贴片机检测系统要求,为相关行业贴片机的检测系统提供一定工程应用参考价值。展开更多
基金the financial support from the National Defense Pre-research Foundation
文摘As a three-dimensional layer enhancement technology, the Z-pin technology is suitable for manufacturing composite prepreg laminates and can also effectively improve their interlaminar properties. In order to manufacture Z-pin composite parts efficiently, this paper proposes a transi- tional insertion system, and according to the technical requirements of the transitional insertion process and the functional requirements of the transitional insertion platform, proposes a transition insertion plan which can insert multiple Z-pins into a carrier. A prototype machine has been designed and made, and a series of function debugging and verification experiments have been car- ried out on the machine. Some problems show up during the experiments, but based on the analysis of the reasons, this paper provides lots of solutions, and finally demonstrates the feasibility and practical value of the system. The results show that the system meets all technical requirements of the Z-pin insertion process. It is capable to insert multiple Z-pins into a foam carrier; as a result, the system is as much as 5 times more efficient than existing equipment, and the deviation for the insertion distance can be controlled within 0.3 mm. This Z-pin transitional insertion platform pro- motes the use of Z-pins in national defense and lays the foundation for commercializing the Z-pin technology.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339801)the National High Technology Research and Development Program of China(Grant No.G060104012AA8122007B)
文摘A backward wave amplifier（BWA） in a terahertz regime with a novel slow-wave structure（SWS） composed of multi parallel grating pins inside a rectangular waveguide is analyzed. The multi-pin rectangular waveguide SWS possesses good performance and is compatible with micro-fabrication technologies. The dispersion and interaction impedance of the multipin SWS are presented. The stopbands of the modes cling together in a Brillouim zone. The SWS has a high interaction impedance that is suitable for the interaction of multi cylindrical beams. The design, which is based on three parallel pins supporting the wave–beam interaction with four cylindrical beams, is verified by three-dimensional particle-in-cell simulations. A BWA with the central frequency at 340 GHz is demonstrated, and the output power is more than 100 mW.A tuning frequency range of 15 GHz（333–348 GHz） is obtained with a gain of more than 20 dB.
基金supported by National Natural Science Foundation of China (No.50678031)
文摘Removal of single component and binary mixtures of benzene and m-xylene using a multi-pin-mesh reactor was studied to find the decomposition characteristics, carbon balance and CO2 selectivity. The decomposition rate of benzene in mixture was approximately 16% lower than that of single component benzene. However, the decomposition rate of m-xylene in mixture was slightly higher than that of single component m-xylene. Carbon balance of the mixture decomposition process achieved a lower level than that of single component benzene/m-xylene. Increase in the specific input energy was helpful to improve CO2 selectivity in the single component decomposition process, while the specific input energy had a negligible effect on CO2 selectivity in the mixture decomposition process. By changing the oxygen content in background gas, we found that different types of radicals showed different reaction activities toward benzene and m-xylene. Benzene was more likely to react with nitrogen-containing radicals, while m-xylene was more likely to react with oxygen-containing radicals.
文摘小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失效。本研究以SOP和BGA元件为研究对象,提出一种结合图像融合差分、缺陷连通域标记和基于倾斜前后引脚外边缘中心点距离变化比对方法的多级引脚缺陷检测方法,以实现元件引脚缺陷的准确检测。实验结果表明,矩形引脚元件SOP和球形引脚元件BGA的总体检测准确率达到了95%以上,且缺陷检测的整体平均耗时均在100ms以内,满足贴片机检测系统要求,为相关行业贴片机的检测系统提供一定工程应用参考价值。
