气波增压柴油机的排气系统改进分析

简要的综述了气波增压柴油机的现状,并对气波增压柴油机排气系统改进原理进行了说明。对排气系统的设计根据有关资料进行了分析与计算论述。根据气波增压器的特点,论述了对改进后排气系统的要求。     

内绝热层的炭化厚度和设计厚度计算

根据内绝热层在固体火箭发动机中的作用,对其提出了若干要求;根据内绝热层的烧蚀机理,推导出内绝热层炭优厚度计算公式;根据燃烧室壳体对热防护的要求,给出了确定内绝热层设计厚度的方法。     

非常规天气航空成像建模与仿真方法研究

给出了雨雾天气下户外场景图像仿真的具体流程,重点分析了点扩展函数对图像 的影响,提出了根据截止角频率将一维调制传递函数转换成二维的点扩展函数的方法。仿真 系统能根据不同的气象数据及无污染场景条件下的图像对不同天气状况下的雨雾图像进行仿 真。
     

用于新型雷达/红外无源复合诱饵的等离子体参数选择

根据电磁波在分层介质中阻抗匹配原理,计算了非均匀非磁化等离子体平行与垂直极化波的功率反射系数。基于碱金属盐的高温电离特性,以功率反射系数为研究对象,对雷达无源诱饵用等离子体的厚度、温度和电子密度分布等参数选择进行了分析,并根据所选择的参数讨论了入射角对无源诱饵应用的影响。     

变推力发动机仿真计算分析

分析了变推力发动机采用的双调模式,用流量调节器控制推进剂流量。流量定位针栓式喷注器控制喷注压降,保证喷注速度基本不变。根据发动机系统特点建立了主要组件的数学模型,并根据模型进行了仿真计算,最后对发动机前管路流阻影响进行了分析。     

导弹武器面临电磁环境的分级方法研究

分析了典型电磁环境分级方法存在的不足之处,根据目前实际需求,对导弹武器面临的电磁环境提出了一种新的分级方法。首先,根据作战规模的大小分为四个等级,然后根据作战过程中干扰战术和技术的使用,在各级中再细分类型。最后,利用电磁环境指标（电磁功率密度谱和电磁信号密度）,实现定量描述,支撑导弹武器抗干扰性能的定量考核。     

双元统一推进系统混合比调节技术研究

对空间液体推进系统的混合比调节技术进行了研究.根据闭环补气调节混合比原理,建立了补气调节混合比试验模型,研究了系统的流量特性.根据某同步轨道卫星平台推进系统的性能要求,给出了相应混合比的调节范围和对应的补气量,为混合比调节技术的实际工程应用提供了理论和试验依据.     

泵压式上面级发动机性能精度干扰因素研究

性能精度是液体火箭发动机的一项重要指标,对于上面级发动机性能精度尤其重要.以某型泵压式上面级发动机为研究对象,利用影响分析树的方法识别了发动机生产、测试、性能调整过程中影响性能精度的干扰因素;针对所识别的干扰因素,通过仿真计算,得到了其偏差对发动机推力和混合比的影响.根据统计学原理,推导得到多项干扰因素影响概率的计算模型,并利用小子样样本对计算模型和程序的正确性进行了验证.利用该概率计算模型,根据置信水平要求,确定了多项干扰因素对发动机性能的极限偏差影响.根据发动机性能精度要求,分解得到了单个干扰因素的控制目标.     

自动对接装配技术在航天产品对接装配中的应用研究

根据国内外自动对接装配技术的发展现状,指出航天企业产品对接装配技术存在的差距。针对航天产品结构特点的发展,对自动化对接装配技术在其领域应用的可行性进行了分析探讨,并根据航空已有的自动对接装配系统组成,制定了航天产品自动对接装配的技术方案。     

补偿卫星轨道运动和热变形对成像的影响

研究了星地一体化补偿卫星轨道运动和结构热变形对载荷成像的影响。首先,根据图像配准的目标,定义了扫描角、步进角和固定网格。然后,根据卫星轨道运动和结构热变形对扫描镜成像影响的特点,设计了运动补偿方案和模型。最后,基于所设计的补偿模型进行了数学仿真,仿真结果表明,星地一体化补偿卫星轨道运动和结构热变形对扫描镜成像的方案可行,能够提高有效载荷的成像质量,满足图像配准指标要求。     

多自由度微振动环境时域波形复现的数值仿真

为满足航天器微振动环境模拟的需要,开展了多自由度微振动时域波形复现控制方法研究。首先,介绍了基于时域波形复现的多自由度微振动环境模拟控制理论方法。其次,针对六自由度微振动激励系统,应用MATLAB软件建立了基于实测传递函数矩阵的多输入多输出微振动激励仿真系统,针对微振动时域波形复现闭环控制过程进行了算法编程,并给出了仿真的闭环控制流程图。最后,通过算例对多自由度微振动时域波形复现进行了数值仿真,以给定的白噪声为输入,模拟对实际存在的系统非线性、测量误差等影响因素的控制效果。仿真结果验证了多自由度微振动时域波形复现控制方法的可行性及有效性,所得结论可以为研究多自由度微振动时域波形复现控制系统提供参考。     

降落伞特性对伞舱系统运动稳定性的影响

建立了伞舱系统刚性连接和弹性连接时的数学模型,针对联盟号飞船回收系统进行了动力学仿真。分析了降落伞侧向力系数、吊带长度、降落伞和载荷质量比以及吊带性质对伞舱系统运动稳定性的影响,其结论可为伞舱回收系统的设计提供参考。     

基于刚体转动四元数模型的航天器再定向方案

介绍了一种新的刚体转动的四元数模型。这些模型可以提高再定向控制的对边界条件的适应能力，在此基础上还介绍了这些模型的一些实际应用。     

On solving the problems of optimization of trajectories of many-revolution orbit transfers of spacecraft

The problem of optimal control over many-revolution spacecraft orbit transfers between circular coplanar orbits of satellites is considered. The spacecraft flight is controlled by a thrust vector of a jet engine with restricted thrust (JERT). The mass expenditure is minimized at a limited time of flight. The optimal control problem is solved based on the maximum principle. The boundary value problem of the maximum principle is solved numerically using the shooting method. A modified computation scheme of the shooting method is suggested (multi-point shooting), as well as a method (correlated with the scheme) of choosing the initial approximation with the use of a solution to the optimization problem in the impulse formulation. The scheme and method allow one to construct many-revolution spacecraft orbit transfers.     

Determination of an Estimation of Parameters of Motion of a Spacecraft on the Stage of Its Descent on the Basis of Integration of Inertial and Optoelectronic Navigation Systems

The problem of determining an estimation of current spacecraft motion parameters on the stage of its descent is solved on the basis of readings of an optoelectronic navigation system and additional information from the self-contained inertial navigation system at the most general assumptions on the nature of motion of the object and the statistical properties of the noise of the measuring devices.     

Determination of parameters of attitude motion of a small communication satellite using the data of measurements of current of solar panels

A communication satellite (small spacecraft) injected into a geosynchronous orbit is considered. Flywheel engines are used to control the rotational spacecraft motion. The spacecraft after the emergency situation has passed into a state of uncontrolled rotation. In this case, no direct telemetric information about parameters of its rotational motion was accessible. As a result, the problem arose to determine the rotational satellite motion according to the available indirect information: current taken from the solar panels. Telemetric measurements of solar panel current obtained on the time interval of a few hours were simultaneously processed by the least squares method integrating the equations of rotational satellite motion. We present the results of processing 10 intervals of the measurement data allowing one to determine the real rotational spacecraft motion and to estimate the total angular momentum of flywheel engines.     

A study of evolution of spin-up mode of a satellite in the plane of its orbit

We investigate the mode of spinning up a low-orbit satellite in the plane of its orbit. In this mode the satellite rotates around its principal central axis of the minimum moment of inertia which executes small oscillations with respect to the normal to the orbit plane; the angular velocity of the rotation around this axis several times exceeds the mean orbital motion. Gravitational and restoring aerodynamic moments are taken into account in the satellite’s equations of motion. A small parameter characterizing deviation of the satellite from a dynamically symmetric shape is introduced into the equations. A two-dimensional integral surface of the equations of motion, describing quasi-steady-state rotations of the satellite close to cylindrical precession of the corresponding symmetrical satellite in a gravitational field, has been studied by the method of small parameter and numerically. Such quasi-steady-state rotations are suggested to be considered as unperturbed motions of the satellite in the spin-up mode. Investigation of the integral surface is reduced to numerical solution of a periodic boundary value problem of a certain auxiliary system of differential equations and to calculation of quasi-steady-state rotations by the two-cycle method. A possibility is demonstrated to construct quasi-steady rotations by way of minimization of a special quadratic functional.     

采用经纬仪测量航天相机视轴的方法分析

在卫星地面总装时,需要测量航天相机视轴之间以及相机视轴与其他敏感仪器或整星坐标系坐标轴之间的角度关系。文章以某线阵CCD相机的安装测量为例,介绍了使用经纬仪系统确定航天相机视轴的方法以及相机与相机之间、相机与整星坐标系坐标轴之间角度关系的测量。分析中对相机的光学系统进行了简化,重点介绍了测量方法的数学模型,并通过误差传递公式分析了测量精度,最后针对该测量方法的不足提出了改进措施。     

Evolution of motion of two viscoelastic planets in the field of forces of their mutual attraction

Translational-rotational motion of two viscoelastic planets in a gravitational force field is studied. The planets are modeled by homogeneous isotropic viscoelastic bodies. In their natural undeformed state each of the planets represents a sphere. We investigate a specific case when the planet’s centers of mass move in a fixed plane, the axis of rotation for each planet being directed along the normal to this plane. An equation describing the evolution of a slow angular variable (perihelion longitude) is derived. The observed displacement of the perihelion of Mercury is compared with the results obtained in the considered model problem about motion of two viscoelastic planets. Quite important is the fact that the planet of smaller mass (Mercury) moves not in a central Newtonian field of forces, but rather in the gravitational field of a rotating viscoelastic planet (Sun).     

The Solution of Some Problems of Optimizing the Processes of a Flexible Correction of Motion of Satellite Systems: II.

In a previous paper [1], as a result of group-theoretic decomposition, one of the problems of the optimization of the flexible correction process was reduced to a series of subproblems. In this paper, the analytical solutions to these subproblems are obtained by the sweep method. A series of other similar problems with different variants of flexibility is also considered; the decomposition of these problems is performed, and their analytical solutions are presented. It is shown for some numerical examples that flexible corrections require essentially lower fuel consumption than the rigid correction, where all parameters characterizing the absolute motion of a satellite system are corrected to their nominal values.