Stable inversion and parameter variations

As part of the process of automatically guiding an aircraft, we have been successful in using stable inversion to compute a desired bounded state trajectory and corresponding bounded control. In addition to this feedforward control, we must also construct a regulator to address modeling errors and disturbances. With respect to modeling errors we find that the stable inversion procedures used are so accurate that the regulator can assume a simple form, say a linear regulator about the desired trajectory. We show that under the appropriate assumptions, the bounded state trajectory and bounded control computed through stable inversion depend continuously on the parameters of the system. This is a consequence of a mathematical result that we prove about the continuous dependence of the “particular solution” of a time varying nonlinear system driven by a bounded input. This is distinct from the usual continuous dependence of the initial value problem for systems.     

BGP仿真系统的设计与实现

BGP是当今唯一在Internet上广泛使用的域间路由协议，其稳定性已经成为影响Internet发展的重要问题之一。BGP仿真系统是研究BGP稳定性的主要手段，该文充分利用了面向对象技术所提供的继承、封装和多态等技术特性，设计并实现了一种具有较好的可扩展性和较高的可维护性BGP仿真系统。     

Analytical impact time and angle guidance via time-varying sliding mode technique

To concretely provide a feasible solution for homing missiles with the precise impact time and angle, this paper develops a novel guidance law, based on the nonlinear engagement dynamics. The guidance law is firstly designed with the prior assumption of a stationary target, followed by the practical extension to a moving target scenario. The time-varying sliding mode (TVSM) technique is applied to fulfill the terminal constraints, in which a specific TVSM surface is constructed with two unknown coefficients. One is tuned to meet the impact time requirement and the other one is targeted with a global sliding mode, so that the impact angle constraint as well as the zero miss distance can be satisfied. Because the proposed law possesses three guidance gain as design parameters, the intercept trajectory can be shaped according to the operational conditions and missile׳s capability.To improve the tolerance of initial heading errors and broaden the application, a new frame of reference is also introduced. Furthermore, the analytical solutions of the flight trajectory, heading angle and acceleration command can be totally expressed for the prediction and offline parameter selection by solving a first-order linear differential equation. Numerical simulation results for various scenarios validate the effectiveness of the proposed guidance law and demonstrate the accuracy of the analytic solutions.     

基于模糊逻辑的导弹扩展比例导引律

临近空间高超声速大机动目标的拦截制导律一直是现代制导与控制方面的一个难点和热点。运用模糊逻辑的方法，改进了扩展比例导引律，使导弹在拦截过程中能够有效跟踪导弹至目标视线转率的变化及目标的机动加速度，拦截末段视线转率收敛，实施成功拦截。     

Designing the NGC system of a small ASV for tracking underwater targets

The paper describes the development of the Navigation, Guidance and Control system of a small, prototypal Autonomous Surface Vehicle (ASV), which is part of an ASV/UUV (Unmanned Underwater Vehicle) robotic system. The main task of the ASV is to serve as supply vessel for the UUV it can carry, deploy and recover and to allow communication with a remote control station. The main problem the NGC system has to handle is that of making the ASV track the UUV and maintain the relative distance within a given bound, using delayed information about the UUV position provided by an acoustic tracking and positioning systems. The specific tracking problem is formulated in a suitable way and a strategy for its solution is proposed and implemented by means of an appropriate control architecture. Stability is discussed using Lyapunov techniques and performances are shown by means of simulations.     

Transient and steady states of Gd2Zr2O7 and 2ZrO2∙Y2O3 (ss) interactions with calcium magnesium aluminium silicates

Reactions between calcium magnesium aluminium silicates (CMAS) and Gd₂Zr₂O₇ or 2ZrO₂?Y₂O₃ (ss) are investigated within a temperature range of 1200–1300 °C and for durations of 1 h–100 h. The evolution of CMAS penetration depth in Gd₂Zr₂O₇ and 2ZrO₂?Y₂O₃ (ss) pellets varies considerably depending on the interaction time. A quantitative analysis of the nature and composition of phases observed in stationary conditions (powder/powder interaction) is performed by SEM-FEG coupled with WDS analyses using micro-agglomerated nanoparticles of Gd₂Zr₂O₇ and 2ZrO₂?Y₂O₃. Faster kinetics of the gadolinium-based system are illustrated through an analysis of the morphology of the reaction area and of the resulting CMAS tightness of reaction products. The compositions and quantities of reaction products observed at equilibrium are very similar for the two systems, but transient states are significantly different.     

Adaptive internal model guidance law for weaving maneuvering target

For the terminal phase guidance problem of the missile intercepting weaving maneuvering target, an adaptive internal model guidance laws in the three-dimensional (3-D) engagement space is proposed in this paper. The guidance law adopts the disturbance rejection theory by treating the target weaving maneuvering accelerations as external disturbance, which comprises of nominal part and adaptive part. The nominal part based on feedback linearization method ensures the whole guidance system stable and the adaptive part based on internal model principle is used to recover the disturbance signals on-line to reject the target maneuver asymptotically. The algorithm guarantees the whole guidance system with satisfying performance both in transient and steady state on the effect of target maneuver on guidance system. The stability analyses and theory proof are provided in this paper. At last, numerical simulations are carried out to illustrate the effectiveness of the proposed guidance law.     

规划·规范·规则:深圳开发控制三大体系的互动关系

规划、规范和规则是建设项目审批依据的三个基本来源,三者共同构成开发控制管理制度的三大核心体系。研究结合深圳实践,阐述三大体系的特征、构成和分类,分析三者在静态条件下的优先关系和在动态条件下的互动关系,尝试揭示三大体系之间相互替代、补充、促进、转化和融合的演化规律。     

基于制导引信一体化的自适应起爆控制

引信与导引头一体化( GIF)设计是提高引战配合效率的有效途径.结合一般雷达导引头,首先介绍一种波控引信与硬件一体化引信进行设计,提出一体化引信起爆控制的逻辑算法流程;然后建立基于GIF信息条件下和基于引信自身信息条件下的两种弹目交会模型,并推导了最佳起爆角、起爆延时的数学表达式;最后分析计算几种弹目交会条件下,多普勒...