3D printing,as one of the most important technologies representing the national aerospace strength,now plays a crucial role in the development of the space industry.The use of space 3D printing technology provides new opportunities for future diversified and oversized space structures by eliminating the constraints and limitations imposed as a result of terrestrial manufacturing and reducing the cost and risk of prefabrication on Earth and transportation to space.3D printing technology enables the direct fabrication of massive antenna structures and space solar power satellites in space,thereby no longer being limited by the size and weight of ground-based fabrication,which will provide a more flexible and efficient solution for the utilization of space resources and future space exploration.This paper introduces the origin and development background of 3D printing technology in space,discusses the research progress of 3D printing technology in space at home and abroad in the fields of on-orbit manufacturing,large-scale space structure construction and planetary bases,elucidates the main features and problems of the relevant technology in its current progress,as well as describes the way forward for its future development.Finally,combining the current development of domestic and foreign technologies and research results,the paper proposes China's future research vision of building large-scale space antennas and space solar power satellite in space,which provides reference and guidance for the realization of 3D printing technology on orbit.
In this paper a kind of solid state power controller was designed and fabricated using thick film hybrid circuit technology. The key fabrication processes such as components relow process and stick process were studied and finally the batch production was realized. Solid state power controller products went through the screening test according to General Specification for Hybrid Integrated Circuits（GJB 2438B—2017）. The screening procedure includes thermal shock, high temperature power burn-in test, constant acceleration, hermetic sealing test and particle impact noise detection（PIND）. Also, 1000h life test was applied to samples after the screening test. The internal water vapor content was measured which is far below the requirement of Test Methods and Procedures for Microelectronic Device（GJB 548B—2005）.
本文基于 MOCVD 欧姆再生长技术,制备了高性能的 AlGaN/GaN HEMTs.器件具有0.16 Ω·mm的低欧姆接触电阻,并且在 100 K到 425 K的温度范围内,欧姆接触电阻表现出良好的热稳定性.由于欧姆接触电阻的改善,源漏间距Lsd为2 μm,栅长Lg 为100 nm的器件的最大饱和电流密度ID,max为1350 mA/mm,跨导峰值Gm,max为372 mS/mm,导通电阻Ron为1.4 Ω·mm,膝点电压Vknee为1.8V.此外,器件也表现出优异的射频特性,电流增益截止频率fT 为 60 GHz,最大振荡频率fmax为109 GHz,在3.6GHz下,VDS偏置在15 V,器件的功率附加效率PAE为67.1%,最大输出功率密度Pout为3.2 W/mm;在30 GHz下,VDS偏置在20 V,功率附加效率PAE为43.2%,最大输出功率密度Pout为5.6 W/mm,这表明了基于MOCVD欧姆再生长技术制备的AlGaN/GaN HEMTs器件在Sub-6G以及毫米波波段的应用中具有巨大潜力.
低轨星座网络流规划方法是提升大型星座网络性能的关键技术.针对现有低轨星座网络流规划方法手段单一,难以兼顾全局性能优化与卫星自主灵活性等问题,研究提出了一种基于组合策略的低轨星座网络流规划方法,首先根据业务特点对网络流进行分类映射,针对6 类映射业务的QoS差异,分别采用集中式、分布式和源端路由等路由控制策略;在此基础上将星座网络流规划问题抽象为求解带宽约束下的多源单汇网络最大流和多源多汇网络最大流问题,分别采用负载均衡路由和多约束QoS路由算法;对基于组合策略和单一策略的星座网络流规划方法进行了仿真分析,结果表明组合策略比集中式的传输时延低约20 ms,丢包率低约9%,比分布式的带宽利用率高约42%,可有效提升星座网络性能,能够更好满足不同场景及需求.
This paper presents a hybrid event-triggered synchronous control method for a master-slave neural network subject to deception attacks.The proposed method employs a hybrid event-triggered scheme based on Bernoulli distribution to reduce the communication burden and handle the unpredictable network environment by transmitting data only when necessary.Notably,the memory event trigger mechanism can transmit more data during the peak and bottom of the system's response state.To account for uncertainties in the system,including network-induced delay and randomly occurring deception attacks are developed within a unified framework and the corresponding Lyapunov-Krasovskii functional(LKF)is constructed.A stabilization criterion is then derived using Lyapunov theory.Numerical simulations demonstrate the effectiveness of the proposed method.
