亚轨道飞行器能量管理段轨迹设计

亚轨道飞行器（SRLV）通过跟踪特定的轨迹来实现对能量的控制与管理,轨迹设计是能量管理的一项关键技术。深入研究了亚轨道飞行器能量管理段（TAEM）轨迹的设计思想、准则和流程;提出了一种基于待飞距离规划动压剖面的轨迹设计方法,通过调整航向调整段的动压剖面,保证飞行器以亚声速状态进入航向调整段,避免飞行器转弯超调;提出了采用顺风作为轨迹设计的缺省状态,保证飞行器在严重的逆风状态下仍然可以满足着陆窗口约束;通过具体算例进行仿真分析,验证了设计方法的有效性。     

沸石分子筛对航天器分子污染物的吸附性能研究

针对空间环境中有机污染物沉积在航天器敏感部件上造成相关功能失效问题,提出一种利用沸石分子筛多孔结构在轨清除有机污染物的新方法。研究了真空环境中,Naβ、NaY、13X三种分子筛对某型号电缆真空放气产物的吸附能力,结果表明13X的吸附能力优于其它两种分子筛,饱和吸收率为14.03%。将其作为分子吸附器的吸附材料应用到航天器易污染的部位,将会有效控制航天器在轨运行的污染水平,提高可靠性。     

卫星遥感农业监测系统中实例检索算法研究

针对智慧农业中需求获取手段、表达方法等导致智能设计算法复杂度高、可用性低等问题，将卫星遥感技术和网络技术结合实现农作物及其生长环境参数的实时监测，以优化播种机设计的需求特征，并以此为基础，提出基于混合相似度的实例检索模型。在该模型中，设计了多级实例库结构，并以特征间距离相似度、特征间可拓关联度、特征间可拓距测度为组成要素，构造多级混合相似度的层次结构与计算方法，进行多级实例检索。将其应用到铲式播种机的数字化设计系统中，可获得与目标实例最相似的实例。实验结果表明，在实例的特征值数据类型多样化的情况下，此算法能够有效地检索出合适的历史实例，提高检索结果的可用性。     

卫星遥感农业监测系统中权重优化的实例修改算法

针对播种机设计过程需求获取的复杂性和可用性低等问题，采用遥感等技术动态监测土壤、农作物生长过程中的一些参数，以优化设计需求特征，并以此为基础，提出改进的混合权重实例修改算法。该算法以相似实例检索为前提，以相似实例集中的特征相似度、问题-解特征间的关联度、问题特征间的自相关度为因子，通过矩阵乘法来构造解特征混合权重矩阵，进行实例修改。将其应用到铲式播种机的数字化设计系统中，以实现智能设计。研究结果表明新算法能有效提高机械设计结果的可用性和准确度。     

Kalman filtering for GPS/magnetometer integrated navigation system

This paper investigated the data processing method for a GPS/IMU/magnetometer integrated system with Kalman filtering (KF). As a result of GPS/IMU/magnetometer land vehicle system, dead-reckoning of magnetometer and accelerometer integrated subsystem bridged very well the GPS signal outage due to the trees on the two sides of the road. Both differential GPS data processing method and the carrier-phase method with magnetometers’ outputs for predicting the car position, velocity, and acceleration (PVA) are presented. The results from DGPS with Kinematical Positioning (KINPOS) software shown that the averages of the north, east, and down direction standard deviation (short for “std”) are 0.014, 0.010, and 0.018 m, respectively. The std of velocities and accelerations derived by the position and velocity differentiation are 10, 7, 13 mm/s, 7, 5, 9 mm/s², respectively. This method for getting velocities and accelerations requires higher accurate position coordinates. But the position accuracy has frequently been degraded in this case when the car drove under the trees or other similar kinematical environments. That caused the larger velocity and acceleration errors. While the results from the carrier-phase method are std of the velocities = 2.1 mm/s, 1.3 mm/s, 3.7 mm/s in north, east, down, and std of the accelerations = 1.5 mm/s², 0.9 mm/s², 2.3 mm/s² for the static test period; as compared with KINPOS software results, std of the velocity difference between the carrier-phase method and the DGPS method = 7 mm/s, 6.9 mm/s, 9.7 mm/s in north, east, down direction, and std of acceleration difference = 5.0 mm/s², 4.5 mm/s², 7.5 mm/s² in north, east, down direction for the kinematical test period. Obviously, errors come from both the carrier-phase method and DGPS velocity and acceleration results derived directly by the position differentiation. In addition, better accuracy of positions than that before KF has been got by means of velocities and accelerations derived by the carrier-phase method after KF.     

低频靶标法测量CCD相机调制传递函数的仿真

基于用高频靶标法测试调制传递函数（MTF）时不能准确地体现出CCD器件的平均采样的情况。该文探讨用低频靶标法测试MTF，介绍它的原理；通过数字仿真CCD的光学镜头的模糊和采样平均过程，分析不同频率靶标的MTF测试结果，并分析相位造成的影响。     

航空发动机H∞/LTR控制试验验证

 用半物理模拟试验验证了多变量鲁棒控制在航空发动机中的应用,给出了航空发动机中H_∞/LTR控制模块的设计过程及注意事项。从半物理模拟试验结果可见:与LQG/LTR控制器不同,H_∞/LTR控制器能在半物理模拟试验环境下稳定控制航空发动机;H_∞/LTR控制器具有优良的噪声抑制功能;基于包线内一点设计的H_∞/LTR控制器可适用于包线内其他区域的加力与非加力状态下的爬升、加速等仿真试验,验证了H_∞/LTR方法的鲁棒性。推进了多变量鲁棒控制设计方法在航空发动机中的实际应用。     

Static Radical Stiffness and Contact Behavior of Nonpneumatic Mechanical Elastic Wheel

Conventional pneumatic tires exhibit disadvantages such as puncture,blowout at high speed,pressure maintenance,etc. Owing to these structural inevitable weaknesses,non-pneumatic tires have been developed and are investigated. A non-pneumatic mechanical elastic wheel(NPMEW)is introduced and investigated as a function of static radical stiffness characteristics and contact behavior. A bench test method is utilized to improve the riding comfort and the traction traffic ability of NPMEW based on tire characteristics test rig,and the static radical stiffness characteristics and the contact behavior of NPMEW are compared with that of an insert supporting run-flat tire(ISRFT). The vertical force-deformation curves and deformed shapes and contact areas of the NPMEW and ISRFT are obtained using a set of vertical loads. The contact behavior is evaluated using extracted geometrical and mechanical feature parameters of the two tires. The results indicate that the NPMEW appears to exhibit considerably high radical stiffness,and the numerical value is dependent on the mechanical characteristic of the flexible tire body and hinge units. NPMEW demonstrates more uniform contact pressure than ISRFT within a certain loading range,and it can efficiently mitigate the problem of stress concentration in ISRFT shoulder under heavy load and enhance the wear resistance and ground grip performances.     

富油/焠熄/贫油(RQL)燃烧室燃烧和排放特性的实验研究

针对燃气轮机低排放燃烧室的研究,设计了以甲烷为燃料采用预混燃烧的富油/焠熄/贫油(RQL)模型燃烧室。通过对RQL模型燃烧室内轴向温度和组分浓度分布,燃烧室出口温度分布及排放进行实验研究,分析了焠熄与主流空气流量之比,富油区当量比对燃烧性能和排放特性的影响规律。结果表明:典型RQL燃烧方式下富油区火焰颜色较暗,贫油区火焰为淡蓝色,燃烧室内轴线方向温度呈M型分布,NO_x主要在焠熄区生成。CO,UHC和O_2浓度在经历焠熄区时发生突变;出口NO_x和CO排放都较低。保持头部当量比不变,随着焠熄与主流空气流量比的增加,燃烧室出口平均温度下降,NO_x排放下降,CO排放上升。保持焠熄与主流空气流量比不变,富油区当量比小于1.4时,不能再实现RQL燃烧模式。     

石英晶体微量天平辐射效应补偿的初步研究

文章根据我国航天器真空热环境试验污染监测的需要,提出了航天器真空热环境石英天平污染监测的辐射效应问题.通过对石英天平内部结构的热特性分析,设计了具备辐射效应补偿的石英晶体微量天平装置.结合卫星真空热环境下的模拟试验,对这种辐射效应补偿效果进行了验证.