Energy-efficient data collection for UAV-assisted IoT: Joint trajectory and resource optimization

Internet of Things (IoT) can be conveniently deployed while empowering various applications, where the IoT nodes can form clusters to finish certain missions collectively. As energy-efficient operations are critical to prolong the lifetime of the energy-constrained IoT devices, the Unmanned Aerial Vehicle (UAV) can be dispatched to geographically approach the IoT clusters towards energy-efficient IoT transmissions. This paper intends to maximize the system energy efficiency by considering both the IoT transmission energy and UAV propulsion energy, where the UAV trajectory and IoT communication resources are jointly optimized. By applying large-system analysis and Dinkelbach method, the original fractional optimization is approximated and reformulated in the form of subtraction, and further a block coordinate descent framework is employed to update the UAV trajectory and IoT communication resources iteratively. Extensive simulation results are provided to corroborate the effectiveness of the proposed method.     

运载火箭贮箱增压消能器性能仿真与结构方案分析

为了更好地认识液体火箭贮箱增压消能器的工作过程，为消能器的结构方案设计提供支撑，针对典型的锥型和直筒型消能器的结构形式建立仿真模型，使用稳态方法仿真得到气体在消能器内的流场分布情况和消能器内部结构对压力损失和减速效果的影响。根据仿真结果给出消能器结构方案并进行试验，通过试验结果验证了仿真结果的准确性。结果表明：锥型和直筒型消能器的第一层节流结构是造成压力损失的主要部件；对于直筒型消能器，数值仿真的压降大小与试验结果的相对误差为6.3%；入口高速气流直接流经第一层节流结构比先经过扩容再流过第一层节流结构造成的压力损失更大；直筒型消能器的出口面积利用率随着均流筛网距离的增加有着先增加后减小的特点；样条曲线样式的导流锥能提高消能器的出口面积利用率。对贮箱增压消能器内部流场的数值仿真可以为消能器结构设计提供重要依据。     

大气层内固体火箭多约束鲁棒三维能量管理制导

针对固体运载火箭大范围精确调节终端约束的要求，提出一种新型的大气层内鲁棒三维能量管理制导方法，通过在线规划侧向速度能力曲线消耗剩余发动机能量。将终端约束表示为关于攻角和速度能力曲线参数的方程组，将闭环制导问题转化为方程组的求解。针对飞行过程中的动压、过载，以及控制变化率等过程约束，构造了攻角和速度能力曲线的可行边界。针对气动系数和发动机参数的不确定性，采用容积卡尔曼滤波器对不确定性进行辨识。仿真结果表明，与模型预测静态规划算法和改进粒子群算法相比，本算法的终端速度调节范围、鲁棒性以及计算效率大幅度提高。     

空间连续型机器人位姿与构型的能量整形控制

针对空间连续型机器人(SCR)位置和姿态机动、连续型机械臂变形控制以及系统受到外界干扰的问题，基于连接与阻尼配置-无源性控制(IDA PBC)方法设计了控制器。通过能量整形得到空间连续型机器人期望的能量函数，再对系统注入阻尼使其渐近稳定。利用非线性干扰观测器估计系统受到的干扰，并对外界干扰进行补偿。仿真结果表明：设计的控制器可以使空间连续型机器人机动到指定的位置和姿态，同时控制连续型机械臂变形为期望的构型，并且具有主动抗干扰的能力。通过选择合适的能量整形系数和阻尼注入系数，可使系统以期望的动态性能到达指定的平衡点。     

Output formation tracking for networked systems with limited energy and aperiodic silence

For leader-following networked systems with the topology switching and the aperiodic silence, limited-energy output formation tracking problems are investigated. Firstly, a new output formation tracking control protocol is proposed, which contains two components associated with the communication interactions between the leader and tracking intelligent agents and the communication interactions among tracking intelligent agents, respectively, and the aperiodic silence, the topology switching and t...     

激光脉冲能量作用下隔离段激波形态及发展控制的数值研究

为了寻求有效的流动控制方法来降低隔离段总压损失，本文基于非定常雷诺平均的Navier-Stokes方程，探究激光脉冲能量沉积对二维及三维隔离段流场马赫反射的控制效果。在来流马赫数分别为1.61和2.51的隔离段流场马赫反射上游，加入脉冲能量沉积，对比激励流场与基础流场，结果表明：能量沉积主要通过高温热核和其诱导的压力波两种方式对马赫反射结构施加作用，显著地影响了马赫反射结构，促使Ma∞ =1.61来流工况下马赫杆的高度减小，马赫反射强度减弱；Ma∞ =2.51来流工况下的马赫反射结构转变为稳定的正规反射，减小了总压损失。控制过程包括：(1)能量沉积产生的局部高温降低当地马赫数，减小马赫反射强度；(2)高温热核诱导的弓形波与马赫反射相互作用，马赫反射结构变形；(3)以反压形式影响马赫反射。     

Formation control for networked multiagent systems with a minimum energy constraint

Minimum-energy formation achievement problems for networked multiagent systems are investigated, where information networks with leaderless and leader-follower structures are respectively addressed and information networks are randomly switching. The critical feature of this work is that the energy constraint is minimum in the sense of the linear matrix inequality, but limited-budget control and guaranteed-cost control cannot realize a minimum-energy formation. Firstly, the leaderless minimum-energy formation control problem is converted into an asymptotic stability one via a nonsingular transformation and state space decomposition, and based on linear matrix inequality techniques, sufficient conditions for analysis and design of leaderless minimum-energy formation achievement are proposed, respectively, which can be solved by the generalized eigenvalue method. Then, main results of minimum-energy formation achievement of leaderless networked multiagent systems are extended leader-follower networked multiagent systems, where the asymmetric property of the leader-follower information network is well dealt with by two nonsingular transformations. Finally, two simulation examples are shown to verify the main results for minimum-energy formation achievements of leaderless and leader-follower networked multiagent systems, respectively.     

GPS接收机的自主完善性监测算法研究

完善性监测是 GPS接收机研制过程中的重要技术问题之一 ,其功能是在接收机不能用于导航服务时向用户提供告警信息。文中对基于最小二乘残差法的 GPS接收机自主完善性监测 (RAIM)算法进行分析与研究 ,并给出了检测门限的求解方法 ,最后对将该算法应用于 GPS/GL ONASS组合接收机时存在的问题进行了探讨。这一算法在某型号接收机的相关实验中取得了较好的效果。