针对通信导航识别系统(Communiction,Navigation and Identification,CNI)中L波段多功能射频综合化的需求,对L波段接收机射频前端电路进行综合化设计。通过分析CNI中航管、塔康、精密测距等L波段功能对接收机的性能需求,结合接收机主要...针对通信导航识别系统(Communiction,Navigation and Identification,CNI)中L波段多功能射频综合化的需求,对L波段接收机射频前端电路进行综合化设计。通过分析CNI中航管、塔康、精密测距等L波段功能对接收机的性能需求,结合接收机主要工作原理和技术指标选取二次变频超外差接收机结构作为实现方案,并对接收机射频前端下变频电路和中频电路进行设计,通过复用前级下变频电路,在中频放大电路中分功能处理实现射频前端综合化设计。计算了两种放大模式下各级器件的增益、噪声系数等指标,结论表明各项指标满足功能设计需求,该射频前端综合化设计方案可以满足CNI系统L波段接收机射频综合化需求。展开更多
In order to improve the safety of the battery of satellite side mounting,and prevent the screw from producing excess due to frequent assembly and disassembly,the YS-20 material replacement and structure optimization d...In order to improve the safety of the battery of satellite side mounting,and prevent the screw from producing excess due to frequent assembly and disassembly,the YS-20 material replacement and structure optimization design of the screw body are carried out under the premise of not changing the original tooling.The double⁃shear test of YS-20 bar is carried out,and the ANSYS optimization design module is used to design 7×7×6,a total of 294,calculation cases of D1,D2,T,the three important dimension parameters of screw structure.The actual bearing state of screw composite structure is accurately simulated by using asymmetric contact model.Three comprehensive evaluations are established,and the calculation examples satisfying the conditions are evaluated comprehensively.The final results are T=12.2 mm,D1=16 mm,D2=2 mm.The stress verification and contact analysis are carried out for the final scheme and the bearing state and contact state optimized screw structure are obtained.展开更多
Value generation is defined as meeting client requirements while minimizing waste. Researchers concur on the issues related to sequential design in handling client requirements, and suggest the use of an integrated de...Value generation is defined as meeting client requirements while minimizing waste. Researchers concur on the issues related to sequential design in handling client requirements, and suggest the use of an integrated design approach as an alternative. Little has been said, however, about the impact of adopting integrated design＇s work organization to traditional design practice, processes and tools, nor about the importance of breaking down socio-cognitive barriers related to mental model fragmentation between design professionals, clients and users. This may result in cognitive inertia, a major source of waste. The objective of this research is to develop and test the introduction of boundary objects, such as new technologies, to the context of integrated teams and organizations to break the cognitive inertia that hinders value generation. The research is conclusive about the effectiveness of using boundary objects to transform practices in construction. This research also contributes to a better understanding of the new purposes of construction projects by framing its context and process dimensions within a theoretical framework, as well as to the evolution of practices in construction - and of practices that could be applicable to other fields.展开更多
文摘针对通信导航识别系统(Communiction,Navigation and Identification,CNI)中L波段多功能射频综合化的需求,对L波段接收机射频前端电路进行综合化设计。通过分析CNI中航管、塔康、精密测距等L波段功能对接收机的性能需求,结合接收机主要工作原理和技术指标选取二次变频超外差接收机结构作为实现方案,并对接收机射频前端下变频电路和中频电路进行设计,通过复用前级下变频电路,在中频放大电路中分功能处理实现射频前端综合化设计。计算了两种放大模式下各级器件的增益、噪声系数等指标,结论表明各项指标满足功能设计需求,该射频前端综合化设计方案可以满足CNI系统L波段接收机射频综合化需求。
文摘In order to improve the safety of the battery of satellite side mounting,and prevent the screw from producing excess due to frequent assembly and disassembly,the YS-20 material replacement and structure optimization design of the screw body are carried out under the premise of not changing the original tooling.The double⁃shear test of YS-20 bar is carried out,and the ANSYS optimization design module is used to design 7×7×6,a total of 294,calculation cases of D1,D2,T,the three important dimension parameters of screw structure.The actual bearing state of screw composite structure is accurately simulated by using asymmetric contact model.Three comprehensive evaluations are established,and the calculation examples satisfying the conditions are evaluated comprehensively.The final results are T=12.2 mm,D1=16 mm,D2=2 mm.The stress verification and contact analysis are carried out for the final scheme and the bearing state and contact state optimized screw structure are obtained.
文摘Value generation is defined as meeting client requirements while minimizing waste. Researchers concur on the issues related to sequential design in handling client requirements, and suggest the use of an integrated design approach as an alternative. Little has been said, however, about the impact of adopting integrated design＇s work organization to traditional design practice, processes and tools, nor about the importance of breaking down socio-cognitive barriers related to mental model fragmentation between design professionals, clients and users. This may result in cognitive inertia, a major source of waste. The objective of this research is to develop and test the introduction of boundary objects, such as new technologies, to the context of integrated teams and organizations to break the cognitive inertia that hinders value generation. The research is conclusive about the effectiveness of using boundary objects to transform practices in construction. This research also contributes to a better understanding of the new purposes of construction projects by framing its context and process dimensions within a theoretical framework, as well as to the evolution of practices in construction - and of practices that could be applicable to other fields.
