Three-dimensional cooperative guidance strategy and guidance law for intercepting highly maneuvering target

Cooperative interception of the target with strong maneuverability by multiple missiles with weak maneuverability in the three-dimensional nonlinear model is studied. Firstly, the three-dimensional nonlinear model of cooperative guidance is established. The three-dimensional reachable region is represented composed of lateral acceleration and longitudinal acceleration in the two-dimensional coordinate system. Secondly, the problem of the multiple missile's reachable coverage area is transformed into the problem of cooperative coverage. A cooperative coverage strategy is proposed and an algorithm for quickly calculating the number of required missiles is designed. Then, the guidance law based on the cooperative coverage strategy is proposed, and it is proved that cooperative interception of the target can be achieved under the acceleration limit. Moreover, the relations among the number of missiles, the initial array position of terminal guidance and the coverage area of the target’s large maneuver are analyzed. The dynamic adjustment strategy of guidance parameters is proposed to reduce the guidance error. Finally, simulation results show that multiple missiles with low maneuverability can achieve effective interception of target with strong maneuverability through the proposed cooperative strategy and cooperative guidance method.     

农村图书馆的困境及发展出路

作为科技兴农的重要教育阵地,建设农村图书馆是实现城乡居民文化平等的根本保障,是促进基层图书馆有序发展的重要手段,是加强农村精神文明建设的根本需要,是推动农村经济发展的基础工程。然而,当前农村图书馆面临着基础设施较为落后、经济投入不足、专业人才严重缺乏、农民意识相对淡薄等问题,这严重阻碍着农村精神文明建设与中国文化教育事业的进步。因此,探索农村图书馆的发展出路势在必行。     

单股自由圆射流撞壁雾化实验

利用直流撞击式喷注器组织燃烧的发动机推力室喉部材料耐温极限制约了发动机燃烧效率提升,一种新型高性能直流冷壁式喷注器可以解决这一问题,为了指导这种新型喷注器的设计,从射流撞击雾化实验出发,探索了圆射流撞壁雾化规律。采用高速摄影捕获溅射雾化场整体形态,利用收集法测量溅射雾化率,选用PDA和PIV分别测量溅射液滴粒径及速度矢量。研究结果表明:射流撞壁后存在溅射,溅射液滴局部呈现螺旋状,液滴粒径为几十微米量级,溅射雾化率随撞击距离的变化规律可分为4个典型阶段:初始段、发展段、稳定段、衰减段,湍流动能为溅射雾化率的决定因素。     

扩频通信系统相偏纠正的一种新方案

文章提出一种新方案,利用同步扩频码不携带载波相位信息的特点来进行相偏纠正的算法避免了相位模糊,可以纠正[0,2π]内的任意相偏,不需要采用锁相环等硬件来实现。     

浅谈新形势下高职院校团建工作的挑战

高校共青团组织作为党联系青年学生的桥梁和纽带,在引导青年学生树立共同理想、服务青年成长成才、全面提高其素质方面负有重要责任。在经济不断开放、不断发展,教育体制不断改革等新的形势下,高校团建工作的开展有了更为广阔的舞台,但同时也面临许多挑战。主要就新的形势下高等职业技术学院团建工作所面临的挑战及如何应对问题作一点浅显分析。     

Model-driven degradation modeling approaches: Investigation and review

The second law of thermodynamics implies that any animate and inanimate systems degrade and inevitably stops functioning. It is irreversible over time that can be labeled as “the degradation arrow of time”. From perspective of products’ reliability design, it is essential to build appropriate models of describing the degradation arrow of time. The current modeling approaches mainly include the model-driven (having assumed forms based on cognitive experience of mankind) and data-driven (using data learning techniques without form hypothesis) approaches. In this paper, we just investigate and review the model-driven degradation approaches, hoping to provide suggestions of the model construction or selection for scholars or engineers. First, for the single mechanism, degradation law models and stochastic process models are classified as separately depicting the tendency and fluctuation of degradation. For the degradation law model, we propose the concept of meta-models as original types for various personal models. For the stochastic process model, two main types including the non-monotonic and monotonical types are presented. Then, four multi-mechanism degradation types are discussed, that are competitive degradation, multi-stage degradation, coexistence of degradation and impact, and coexistence of degradation and failure. Besides, for the multi-performance degradation, independent and coupling models are introduced. The forms, connotations, applicability and insufficiency of these models are described with a series of examples from the literature and our own experiences. The final explicit suggestions about the potential future work are provided for the development of new degradation models.     

基于感生电压的变压器工作原理分析

研究了楞次定律及法拉第电磁感应定律在电机原理分析中容易引起理解错误的原因,提出采用感生电压代替感生电动势来分析电机原理的方法,并应用该方法分析了变压器负载运行时各个变量之间的关系,给出电压、电流平衡方程、等效电路及相量图。     

基于资源环境约束的我国新型城镇化建设探讨

对于我国快速的城市化、多维的城市转型及其相应的社会与空间问题已经经过学者大量的研究,但依然没有得到很好的解答.从资源环境约束的视角出发对城镇发展的若干问题进行探讨,将弥补上述研究的不足,并形成一个新的研究视角及策略空间.     

中国经验与埃及教训——埃及宪政危机的再思考

以动荡持续时间最长、革命最为激烈的埃及为例,＂阿拉伯之春＂的教训发人深省。西方民主宪政是否具有普世性,威权统治模式是否具有合法性,伊斯兰世界教俗关系如何处理,新型媒体与青年运动对社会稳定造成怎样的冲击。总结埃及变局的历史教训,可以为中国的政局稳定提供具体启示。     

基于奇异摄动与反馈线性化的滑翔制导律

针对高超声速再入飞行器最远距离滑翔制导关键技术,设计了一种新型制导律.首先,利用奇异摄动理论对再入飞行器状态变量进行两个时间尺度的划分,将系统状态方程分解成两个低维子系统.然后,应用最优控制理论得出慢时间尺度上的解,并将其作为降维后的最优参考轨迹;在此基础上,利用非线性微分几何反馈线性化方法,设计快时间尺度制导指令,实...