基于相位差渐进循环协调的应急车辆优先信号控制

为了提高应急车辆的通行效率,针对应急车辆需要“绝对优先”路权的特点进行了信号控制的研究,提出了一种基于相位差渐进循环协调的信号控制策略,并将其与应急车辆优先信号配时转换策略相结合进行应急车辆优先信号控制,给出了应急车辆优先信号配时转换控制策略和动态相位差的计算方法。在由三交叉口组成的城市道路系统中,采用三种应急车辆的信号控制策略进行了微观仿真实验,结果表明,文章提出的基于相位差渐进循环协调的应急车辆优先信号控制策略通过对各交叉口相位动态循环渐进微调后,再采用应急车辆优先信号配时转换策略进行控制,可以使应急车辆安全不停车地通过交叉口,且达到了对非应急车辆影响最小的效果。     

State transformation-based dynamic visual servoing for an unmanned aerial vehicle

In this paper, we propose a visual servoing control for a quadrotor unmanned aerial vehicle (UAV) which is based on a state transformation technique. The UAV is equipped with a single downwards facing camera, and the motion control objective is the regulation of relative displacement and yaw to a stationary visual target located on the ground. The state transformation is defined by a system of partial differential equations (PDEs) which eliminate roll and pitch rate dependence in the transformed image feature kinematics. A method for computing the general solutions of these PDEs is given, and we show a particular solution reduces to an established virtual camera approach. We treat point and line cases and introduce image moment features defined in the virtual camera image plane. Robustness of the control design is improved by accounting for attitude measurement bias, and uncertainty in thrust gain, mass, and image feature depth. The asymptotic stability of the closed-loop is proven. The method is based on a simple proportional-integral-derivative (PID) structure which can be readily implemented on-board. Experimental results show improved performance relative to previous work.     

ILP heuristics and a new exact method for bi-objective 0/1 ILPs: Application to FTTx-network design

Heuristics and metaheuristics are inevitable ingredients of most of the general purpose ILP solvers today, because of their contribution to the significant boost of the performance of exact methods. In the field of bi/multi-objective optimization, to the best of our knowledge, it is still not very common to integrate ILP heuristics into exact solution frameworks. This paper aims to bring a stronger attention of both the exact and metaheuristic communities to still unexplored possibilities for performance improvements of exact and heuristic multi-objective optimization algorithms.We focus on bi-objective optimization problems whose feasible solutions can be described as 0/1 integer linear programs and propose two ILP heuristics, boundary induced neighborhood search (BINS) and directional local branching. Their main idea is to combine the features and explore the neighborhoods of solutions that are relatively close in the objective space. A two-phase ILP-based heuristic framework relying on BINS and directional local branching is introduced. Moreover, a new exact method called adaptive search in objective space (ASOS) is also proposed. ASOS combines features of the ϵ-constraint method with the binary search in the objective space and uses heuristic solutions produced by BINS for guidance. Our new methods are computationally evaluated on two problems of particular relevance for the design of FTTx-networks. Comparison with other known exact methods (relying on the exploration of the objective space) is conducted on a set of realistic benchmark instances representing telecommunication access networks from Germany.     

基于分层递阶商空间链的图连通性研究

图连通性的判定对于路径规划中任意两点间路径相通性判断以及连通块的划分都具有重要意义。从节点的边连通关系着手分析图的结构层次,通过构建图的分层递阶商空间链,分析不同层次商空间链中各节点分布情况,得出新的图连通性判定方法。与以往各判定方法相比,该方法具有易实现、效率高的优点,不仅能有效地判定图是否连通,还能确定图的连通分支数以及哪些节点位于同一连通分支中。     

基于改进人工势场法的智能无人车路径规划仿真研究

传统的人工势场法由于存在局部极小值问题,使智能无人车无法到达目标点。本文提出一种角度偏移的改进人工势场方法来进行避障的路径规划。介绍传统人工势场模型,详细介绍改进人工势场方法,并且对改进人工势场法进行仿真,实验证明方法的有效性。     

On partitioning a graph into two connected subgraphs

Suppose a graph G is given with two vertex-disjoint sets of vertices Z₁ and Z₂. Can we partition the remaining vertices of G such that we obtain two connected vertex-disjoint subgraphs of G that contain Z₁ and Z₂, respectively? This problem is known as the 2-Disjoint Connected Subgraphs problem. It is already NP-complete for the class of n-vertex graphs G=(V,E) in which Z₁ and Z₂ each contain a connected set that dominates all vertices in V?(Z₁∪Z₂). We present an O^∗(1.2051ⁿ) time algorithm that solves it for this graph class. As a consequence, we can also solve this problem in O^∗(1.2051ⁿ) time for the classes of n-vertex P₆-free graphs and split graphs. This is an improvement upon a recent O^∗(1.5790ⁿ) time algorithm for these two classes. Our approach translates the problem to a generalized version of hypergraph 2-coloring and combines inclusion/exclusion with measure and conquer.     

求解圆盘图中最小连通支配集的近似算法

针对无线传感器网络常用的拓扑模型单位圆盘图,提出了基于分布式贪心策略的近似算法DDT,在算法执行的每一轮中,根据一跳邻域范围内的权值和邻居的状态信息,选举出节点并和已确定的节点连接,逐步构造出网络图中的一个支配树。用概率方法研究了支配树中的节点度的性质,通过对极大独立集和最小连通支配集之间关系的分析,得到单位圆盘图中最小连通支配集问题一个新的近似比。计算结果表明,和相关的分布式算法相比,DDT产生的连通支配集在规模上更优。     

Structural Synthesis of Modular Weakly Connected Neural Networks. I. Methodology of Structural Synthesis of Modular Neural Networks

Structural models of modular neural networks without loops are considered. The notion of a weakly connected network is introduced. A genetic principle of generation of weakly connected neural networks is proposed, and its reproductive power is proved on the basis of the theory of categories. Algorithmic realizations of structural synthesis are considered. Some examples are given.     

Adaptive guidance law design based on characteristic model for reentry vehicles

In this paper an adaptive guidance law based on the characteristic model is designed to track a reference drag acceleration for reentry vehicles like the Shuttle. The characteristic modeling method of linear constant systems is extended for single-input and single-output （SlSO） linear time-varying systems so that the characteristic model can be established for reentry vehicles. A new nonlinear differential golden-section adaptive control law is presented. When the coefficients belong to a bounded closed convex set and their rate of change meets some constraints, the uniformly asymptotic stability of the nonlinear differential golden-section adaptive control system is proved. The tracking control law, the nonlinear differential golden-section control law, and the revised logical integral control law are integrated to design an adaptive guidance law based on the characteristic model. This guidance law overcomes the disadvantage of the feedback linearization method which needs the precise model. Simulation results show that the proposed method has better performance of tracking the reference drag acceleration than the feedback linearizaUon one.     

区域车辆信息管理系统建设设想

充分利用计算机技术和Internet技术,开展车辆管理和网上服务已成为一种发展趋势,重点介绍了区域车辆信息管理系统的建设设想及软件体系构架。