为提高敏捷挠性航天器在轨连续机动的快速性和高稳定性,应用变速控制力矩陀螺(variable speed control moment gyroscopes,VSCMGs)作为姿态控制执行机构,提出了一种将观测器与自适应控制结合的姿态控制律与VSCMGs复合操纵律。考虑到机...为提高敏捷挠性航天器在轨连续机动的快速性和高稳定性,应用变速控制力矩陀螺(variable speed control moment gyroscopes,VSCMGs)作为姿态控制执行机构,提出了一种将观测器与自适应控制结合的姿态控制律与VSCMGs复合操纵律。考虑到机动过程中挠性模态及精确惯量不可知,采用模态观测器和转动惯量估计器对不可测的状态或参数进行辨识,辨识结果用于精确估计前馈补偿力矩,利用Lyapunov分析方法证明了闭环控制系统的稳定性。鉴于VSCMGs实际使用的力矩分配能力、避奇异能力、轮速平衡能力与末态框架角定位能力,分别设计了加权伪逆操纵律与3种对应的零运动。基于雅可比矩阵条件数提出了末态框架角的优选方法,给出了VSCMGs零运动在机动过程不同阶段的部署方案。结果表明:通过连续姿态机动数值仿真验证了所提算法的有效性;VSCMGs在连续机动过程中平滑切换模式,在不同的机动阶段实现了相应功能。模态观测值和惯量估计值在多次机动后收敛至真值附近,经过参数辨识后的控制器使航天器在机动末端更快更稳地达到指向精度要求。展开更多
Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane is also called diepoxycyclohexylethyl octamethyltetrasiloxane. In the present paper, diepoxycyclohexylethyl octamethyltetrasiloxane was synthesized, and the syn...Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane is also called diepoxycyclohexylethyl octamethyltetrasiloxane. In the present paper, diepoxycyclohexylethyl octamethyltetrasiloxane was synthesized, and the synthesized product was characterized by FTIR and 1 HMR. The synthesized product was compounded with some acrylates and an expoxide as well as photoinitiators to obtain a 3D printing stereolithography resin(3DSLR111). The properties of 3DSLR111 and its UV-cured samples were investigated by some instruments and equipments. The experimental results show that the critical exposure(Ec) of 3DSLR111 is 10.1 mJ/cm^2, its penetration depth(Dp) is 0.15 mm, and its viscosity at 30 ℃ is 319 mPa·s. Some samples were printed with 3DSLR111, and their linear shrinkage and warping factor were evaluated. The linear shrinkage and the curl distortion factor are less than 0.80% and 7.30%, respectively, which indicates that the sample printed with 3DSLR111 has high accuracy, and that the synthesized diepoxycyclohexylethyl octamethyltetrasiloxane can be well applied to the preparation of the photosensitive resin for stereolithography 3D printing.展开更多
A novel cationic photosensitive resin(3 DSLR-01) for stereolithography 3 D printing was prepared with 3,4-epoxycyclohexylmethyl-3’,4’-epoxycyclohexane carboxylate(2021 P),1,4-cyclohexanedimethanol glycidyl ether(JX-...A novel cationic photosensitive resin(3 DSLR-01) for stereolithography 3 D printing was prepared with 3,4-epoxycyclohexylmethyl-3’,4’-epoxycyclohexane carboxylate(2021 P),1,4-cyclohexanedimethanol glycidyl ether(JX-026), diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate(S-186), polycaprolactone polyol(Polyol-0305), novolac epoxy resin(F-51), bis(3-ethyl-3-oxetanylmethyl) ether(S-221) and a mixture of triarylsulfonium hexafluoroantimonate salts solution(UVI-6976). The properties of the photosensitive resin and its UV-cured films were investigated by some instruments and equipment.The experimental results show that the critical exposure(Ec) of the photosensitive resin is 16.3 mJ/cm^2, the penetration depth(Dp) is 0.14 mm, and the optical property of the photosensitive resin is excellent. Rectangle plates were printed by using a stereolithography apparatus(HRPL-150 A) with the photosensitive resin as the manufacturing material, and the shrinkage rates of the plates were less than 0.60%, which showed that the accuracy of the manufactured plates was very high.展开更多
为探究进气口宽度对火旋风燃烧特性的影响,利用自然驱动的四面边墙夹缝式装置对不同进气口宽度使用150,200,250 mm 3种直径进行实验研究。由燃料质量随时间变化曲线得出准稳态阶段火旋风的质量燃烧速率;利用摄像机记录火焰的连续图像并...为探究进气口宽度对火旋风燃烧特性的影响,利用自然驱动的四面边墙夹缝式装置对不同进气口宽度使用150,200,250 mm 3种直径进行实验研究。由燃料质量随时间变化曲线得出准稳态阶段火旋风的质量燃烧速率;利用摄像机记录火焰的连续图像并获得火焰高度。结果表明:针对实验室小型火旋风(150~250 mm),在进气口宽度为35 mm左右时,火旋风的燃烧速率最大,即火旋风的燃烧强度存在1个最佳的进气口宽度;当火焰高度达到最高时,环量也存在1个临界值。展开更多
文摘为提高敏捷挠性航天器在轨连续机动的快速性和高稳定性,应用变速控制力矩陀螺(variable speed control moment gyroscopes,VSCMGs)作为姿态控制执行机构,提出了一种将观测器与自适应控制结合的姿态控制律与VSCMGs复合操纵律。考虑到机动过程中挠性模态及精确惯量不可知,采用模态观测器和转动惯量估计器对不可测的状态或参数进行辨识,辨识结果用于精确估计前馈补偿力矩,利用Lyapunov分析方法证明了闭环控制系统的稳定性。鉴于VSCMGs实际使用的力矩分配能力、避奇异能力、轮速平衡能力与末态框架角定位能力,分别设计了加权伪逆操纵律与3种对应的零运动。基于雅可比矩阵条件数提出了末态框架角的优选方法,给出了VSCMGs零运动在机动过程不同阶段的部署方案。结果表明:通过连续姿态机动数值仿真验证了所提算法的有效性;VSCMGs在连续机动过程中平滑切换模式,在不同的机动阶段实现了相应功能。模态观测值和惯量估计值在多次机动后收敛至真值附近,经过参数辨识后的控制器使航天器在机动末端更快更稳地达到指向精度要求。
基金Funded by the National Natural Science Foundation of China(No.51563017)
文摘Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane is also called diepoxycyclohexylethyl octamethyltetrasiloxane. In the present paper, diepoxycyclohexylethyl octamethyltetrasiloxane was synthesized, and the synthesized product was characterized by FTIR and 1 HMR. The synthesized product was compounded with some acrylates and an expoxide as well as photoinitiators to obtain a 3D printing stereolithography resin(3DSLR111). The properties of 3DSLR111 and its UV-cured samples were investigated by some instruments and equipments. The experimental results show that the critical exposure(Ec) of 3DSLR111 is 10.1 mJ/cm^2, its penetration depth(Dp) is 0.15 mm, and its viscosity at 30 ℃ is 319 mPa·s. Some samples were printed with 3DSLR111, and their linear shrinkage and warping factor were evaluated. The linear shrinkage and the curl distortion factor are less than 0.80% and 7.30%, respectively, which indicates that the sample printed with 3DSLR111 has high accuracy, and that the synthesized diepoxycyclohexylethyl octamethyltetrasiloxane can be well applied to the preparation of the photosensitive resin for stereolithography 3D printing.
基金Funded by the National Natural Science Foundation of China(No.51563017)
文摘A novel cationic photosensitive resin(3 DSLR-01) for stereolithography 3 D printing was prepared with 3,4-epoxycyclohexylmethyl-3’,4’-epoxycyclohexane carboxylate(2021 P),1,4-cyclohexanedimethanol glycidyl ether(JX-026), diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate(S-186), polycaprolactone polyol(Polyol-0305), novolac epoxy resin(F-51), bis(3-ethyl-3-oxetanylmethyl) ether(S-221) and a mixture of triarylsulfonium hexafluoroantimonate salts solution(UVI-6976). The properties of the photosensitive resin and its UV-cured films were investigated by some instruments and equipment.The experimental results show that the critical exposure(Ec) of the photosensitive resin is 16.3 mJ/cm^2, the penetration depth(Dp) is 0.14 mm, and the optical property of the photosensitive resin is excellent. Rectangle plates were printed by using a stereolithography apparatus(HRPL-150 A) with the photosensitive resin as the manufacturing material, and the shrinkage rates of the plates were less than 0.60%, which showed that the accuracy of the manufactured plates was very high.
文摘为探究进气口宽度对火旋风燃烧特性的影响,利用自然驱动的四面边墙夹缝式装置对不同进气口宽度使用150,200,250 mm 3种直径进行实验研究。由燃料质量随时间变化曲线得出准稳态阶段火旋风的质量燃烧速率;利用摄像机记录火焰的连续图像并获得火焰高度。结果表明:针对实验室小型火旋风(150~250 mm),在进气口宽度为35 mm左右时,火旋风的燃烧速率最大,即火旋风的燃烧强度存在1个最佳的进气口宽度;当火焰高度达到最高时,环量也存在1个临界值。
