针对运载火箭推力下降或伺服机构卡死等有限故障,提出了一种基于径向基神经网络(radial basis function neural network,RBFNN)的自适应容错姿态控制方法。该方法在有限故障动力学模型基础上,采用极点配置设计基线控制器,使用RBFNN在线...针对运载火箭推力下降或伺服机构卡死等有限故障,提出了一种基于径向基神经网络(radial basis function neural network,RBFNN)的自适应容错姿态控制方法。该方法在有限故障动力学模型基础上,采用极点配置设计基线控制器,使用RBFNN在线辨识模型的故障参数和不确定干扰,最后基于Lyapunov理论设计自适应容错控制律对故障模型和干扰进行补偿。仿真结果表明,在有限故障工况下,该方法与传统PD方法相比,对故障具有较好的自适应能力,并能满足姿态稳定和控制精度要求。展开更多
This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and di...This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and disruptive technologies, utilizing the concept of low cost manufacturing and operating modes as well. This paper also analyzes the launch strategies for small satellites such as piggyback, networking launch, and single launch with a small launch vehicle(SLV). Finally, the development trend of reusable launch vehicles is discussed as well as the development prospects for China's reusable launch vehicle.展开更多
Heavy launch vehicles represent the ability of a country to enter space and utilize space resources. In re-cent years, with the growth in human space exploration, the major aerospace powers and companies in the world ...Heavy launch vehicles represent the ability of a country to enter space and utilize space resources. In re-cent years, with the growth in human space exploration, the major aerospace powers and companies in the world areplanning to develop heavy launch vehicles. This study analyzes the development of heavy launch vehicles in the world,reviews the characteristics of China's heavy launch vehicle serial configuration, and then proposes common points anddevelopment trends of future heavy launch vehicles in the world.展开更多
The extraction of uranium from aqueous solution is highly desirable for sustaining the increasing demand for environmental safety and nuclear fuel.Herein,we report a strategy using a two-step covalent modification for...The extraction of uranium from aqueous solution is highly desirable for sustaining the increasing demand for environmental safety and nuclear fuel.Herein,we report a strategy using a two-step covalent modification for the synthesis of covalent organic frameworks(COFs)with high-density amidoxime chelate groups at periphery.The introduction of dense amidoxime groups plays a pivotal role in uranium adsorption.The resulting COF exhibits strong affinity with the distribution coefficient of 5.2×104 mL/g and a high adsorption capacity of 319.9 mg/g.The strategy could be expanded to identify and remove different contaminants by introducing special functional groups.展开更多
文摘针对运载火箭推力下降或伺服机构卡死等有限故障,提出了一种基于径向基神经网络(radial basis function neural network,RBFNN)的自适应容错姿态控制方法。该方法在有限故障动力学模型基础上,采用极点配置设计基线控制器,使用RBFNN在线辨识模型的故障参数和不确定干扰,最后基于Lyapunov理论设计自适应容错控制律对故障模型和干扰进行补偿。仿真结果表明,在有限故障工况下,该方法与传统PD方法相比,对故障具有较好的自适应能力,并能满足姿态稳定和控制精度要求。
文摘This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and disruptive technologies, utilizing the concept of low cost manufacturing and operating modes as well. This paper also analyzes the launch strategies for small satellites such as piggyback, networking launch, and single launch with a small launch vehicle(SLV). Finally, the development trend of reusable launch vehicles is discussed as well as the development prospects for China's reusable launch vehicle.
文摘Heavy launch vehicles represent the ability of a country to enter space and utilize space resources. In re-cent years, with the growth in human space exploration, the major aerospace powers and companies in the world areplanning to develop heavy launch vehicles. This study analyzes the development of heavy launch vehicles in the world,reviews the characteristics of China's heavy launch vehicle serial configuration, and then proposes common points anddevelopment trends of future heavy launch vehicles in the world.
基金supported by the National Natural Science Foundation of China(Nos.21975078,22061014)the Guangdong Basic and Applied Basic Research Foundation,China(No.2021A1515010311)+1 种基金the Natural Science Foundation of Guangdong Province,China(No.2019B030301003)the 111 Project,and the Thousand Youth Talents Plan.GU Cheng acknowledges the scholarship support from the China Scholarship Council(No.202006155049).
文摘The extraction of uranium from aqueous solution is highly desirable for sustaining the increasing demand for environmental safety and nuclear fuel.Herein,we report a strategy using a two-step covalent modification for the synthesis of covalent organic frameworks(COFs)with high-density amidoxime chelate groups at periphery.The introduction of dense amidoxime groups plays a pivotal role in uranium adsorption.The resulting COF exhibits strong affinity with the distribution coefficient of 5.2×104 mL/g and a high adsorption capacity of 319.9 mg/g.The strategy could be expanded to identify and remove different contaminants by introducing special functional groups.
