青蒿素及其一类物的结构和合成的研究 XXII: 青蒿丁素的区域选择性合成

本文报导了从青蒿酸所得的烯醇硅醚化合物, 经OsO4的区域选择性羟基化和环合,得青蒿丁素的合成路线.     

Underactuated spacecraft angular velocity stabilization and three-axis attitude stabilization using two single gimbal control moment gyros

Angular velocity stabilization control and attitude stabilization control for an underactuated spacecraft using only two single gimbal control moment gyros （SGCMGs） as actuators is investigated. First of all, the dynamic model of the underactuated spacecraft is established and the singularity of different configurations with the two SGCMGs is analyzed. Under the assumption that the gimbal axes of the two SGCMGs are installed in any direction, and that the total system angular momentum is not zero, a state feedback control law via Lyapunov method is designed to globally asymptotically stabilize the angular velocity of spacecraft. Under the assumption that the gimbal axes of the two SGCMGs are coaxially installed along anyone of the three principal axes of spacecraft inertia, and that the total system angular momentum is zero, a discontinuous state feedback control law is designed to stabilize three-axis attitude of spacecraft with respect to the inertial frame. Furthermore, the singularity escape of SGCMGs for the above two control problems is also studied. Simulation results demonstrate the validity of the control laws.     

An ergodic algorithm for long-term coverage of elliptical orbits

This paper deals with the coverage analysis problem of elliptical orbits. An algorithm based on ergodic theory, for long-term coverage of elliptical orbits, is proposed. The differential form of the invariant measure is constructed via the perturbation on mean orbital elements resulted from the J2 term of non-spherical shape of the earth. A rigorous proof for this is then given. Different from the case of circular orbits, here the flow and its space of the dynamical system are defined on a physical space, and the real-value function is defined as the characteristic function on station mask. Therefore, the long-term coverage is reduced to a double integral via Birkhoff-Khinchin theorem. The numerical implementation indicates that the ergodic algorithm developed is available for a wide range of eccentricities.     

The J2 invariant relative configuration of spaceborne SAR interferometer for digital elevation measurement

A 3-craft formation configuration is proposed to perform the digital elevation model （DEM） for the distributed spacebome interferometric synthetic aperture radar （InSAR）, and it is optimized by the modified ant colony algorithm to have the best compatibility with J2 invariant orbits created by differential correction algorithm. The configuration has succeeded in assigning the across-track baseline to vary periodically and with its mean value equal to the optimal baseline determined by the relative height measurement accuracy. The required relationship between crafts＇ magnitudes and phases is formulated for the general case of interferometry measure from non-orthographic and non-lateral view. The J2 invariant configurations created by differential correction algorithm are employed to investigate their compatibility with the required configuration. The colony algorithm is applied to search the optimal configuration holding the near-constant across-track baseline under the J2 perturbation, and the absolute height measurement accuracy is preferable as expected.     

荧光探针检测香烟主流烟雾活性氧的机理研究

不具有荧光的探针双氢罗丹明6G被氧化后可以生成具有荧光特性的罗丹明6G。反应中,一个双氢罗丹明分子能够与2个活性氧发生作用。借助衍生荧光检测技术,可以将该探针用于香烟主流烟雾活性氧含量的检测实验。利用探针在该实验条件下检测市场上4种品牌香烟的主流烟雾中活性氧的含量,含量分别为：(59.93±5.32)nmol,(55.98±6.17)nmol,(54.78±7.82)nmol,(40.87±6.43)nmol。实验结果表明,香烟主流烟雾中活性氧的含量与烟草品种及制作工艺存在密切的联系。借助荧光特性进行主流烟雾活性氧含量近实时检测的方法具有灵敏度高与检测速度快的特点。     

多体系统动力学Kane方法的改进

基于Kane方法, 针对约束多体系统, 建立了一种新型的自动组集系统动力学方程的方法. 首先提出偏速度矩阵和偏角速度矩阵的概念, 将各体对系统广义惯性力的贡献用简洁、统一的数学形式表达. 然后引入各个运动学变量的递推关系以提高建模效率.最后对新型的Kane方程进行扩展, 用于处理多体系统中的运动约束. 该算法适用于任意多体系统, 建立的动力学模型不含待定乘子, 维数与系统广义速率相同, 利于控制系统设计.对带有闭环约束的空间多机械臂系统的数值仿真验证了方法的正确性.