Costate estimation for dynamic systems of the second order

The dynamics of a mechanical system in the Lagrange space yields a set of differential equations of the second order and involves much less variables and constraints than that described in the state space. This paper presents a so-called Legendre pseudo-spectral (PS) approach for directly estimating the costates of the Bolza problem of optimal control of a set of dynamic equations of the second order. Under a set of closure conditions, it is proved that the Karush-Kuhn-Tucker (KKT) multipliers satisfy the same conditions as those determined by collocating the costate equations of the second order. Hence, the KKT multipliers can be used to estimate the costates of the Bolza problem via a simple linear mapping. The proposed approach can be used to check the optimality of the direct solution for a trajectory optimization problem involving the dynamic equations of the second order and to remove any conversion of the dynamic system from the second order to the first order. The new approach is demonstrated via two classical benchmark problems. Supported by the National Natural Science Foundation of China (Grant Nos. 10372039, 10672073), and the Innovation Fund for Graduate Students of NUAA (Grant No. 4003-019016)     

基于角度不变的线阵推扫式CCD相机几何畸变在轨检校方法

对航天遥感相机进行在轨检校,是提高卫星产品质量,扩大产品应用效果的重要技术内容.文中研究了一种基于角度不变的线阵推扫式CCD相机几何畸变在轨检校方法.该方法利用相机外方元素对于相机视向量夹角角度影响比较小的原理,根据地面控制点和一级产品图像,求解相机视向量夹角,从中提取相机光学部件的畸变模型参数,从而实现相机内外方元素解耦.相机畸变模型采用一维3阶多项式,对焦距和主点等引起的低阶误差能够很好地吸收.该方法用在HJ-1A/B卫星的宽幅盖CCD相机几何畸变校正上,检校误差残留在2—6个像元,和参考数据精度相似,表明取得了很好的校正效果.     

基于面心组合的排气歧管响应曲面优化设计

为解决发动机排气歧管结构优化通常采用单因素控制变量法或正交试验法带来的参数交互作用不显著等局限问题,采用中心复合试验设计(Central Composite Design)方法中的面心组合法构建响应曲面优化.以某重型载货汽车的发动机排气歧管为研究对象,实现了排气歧管38组结构参数的快速匹配,建立了多项式数学模型,得出了...     

无线电监测网络建设的新思考

近几十年来,乘着改革开放的春风,我国的经济持续高速发展,令世人瞩目.无线电业务和各类无线电台站随之快速增加,这使无线电频率需求增长,资源短缺,无线电干扰增多,电磁环境日趋恶化.就广东省而言,据不完全统计,至2005年底,全省除移动通信用户外的无线电台站总数近16万,公众移动电话基站和小灵通基站近10万座,电话用户超过1亿户,有2/3是移动用户,无线电业务已经渗入到人们日常生活的各个方面.这给无线电管理和无线电监测工作带来了机遇和挑战.     

特种磷化液用于电厂蒸汽导气管室温磷化

研究了HH951特种磷化液用于大型电厂蒸汽导气管的室温磷化工艺，并用多种方法对磷化膜质量进行了评价，同时报道了该工艺在多家电厂300MW机组蒸汽导气管的应用。间歇式磷化工艺，能提高磷化膜的耐蚀能力，并大大减少了药品用量，HH951磷化效果优良，实际使用最低磷化温度4℃，完全能满足我国大多数地区的电厂蒸汽导气管清洗磷化的需要。     

Nonlinear dynamics of a planetary gear system with multiple clearances

Presented in this paper is on the nonlinear dynamics of a planetary gear system with multiple clearances taken into account. A lateral–torsional coupled model is established with multiple backlashes, time-varying mesh stiffness, error excitation and sun-gear shaft compliance considered. The solutions are determined by using harmonic balance method from the equations in matrix form. The theoretical results from HBM are verified by using the numerical integration. Finally, effects of parameters are discussed.     

Global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback

This paper presents both analytical and numerical studies on the global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback.Based on a detailed analysis of the stability switches of the trivial equilibrium of the system,the stability charts are given in a parameter space consisting of the time delay and the feedback gains.The center manifold reduc-tion and the normal form method are used to study Hopf bifurcations with respect to the time delay.To gain an insight into the persi...     

燃烧法合成氧化铁催化剂制备碳纳米管

通过硝酸铁柠檬酸凝胶直接自蔓延燃烧反应制备氧化铁体粉末,使用热重-差热分析法（TG-DSC）分析凝胶的合成温度,比较凝胶的先驱体溶液中柠檬酸和硝酸铁的不同比例对氧化铁体粉末结构和形貌的影响,并以此法制备的氧化铁为催化剂制备碳纳米管.使用SEM,TEM对所制备的碳纳米管的结构和形貌进行表伍,XRD分析表明,使用稀盐酸和浓硝酸能有效的除去产物中残留的催化剂颗粒.     

离心式压缩机叶轮主要气动设计参数的分析研究

分析了叶轮进出口气动设计参数的分布规律，通过分析，对叶轮主要气动参数的分布规律有了新的认识，并可为离心式压缩机设计提供一定参考。     

基于电子地图的工地安全监督信息系统建设

利用电子地图作为信息系统的地理空间数据,不仅可以减少系统建设的投入,更能够快速实现基于地理信息技术的管理信息系统建设。