Minimizing makespan in a multimode multiprocessor shop scheduling problem

We study the problem of multimode scheduling tasks on dedicated processors, with the objective of minimizing the maximum completion time. Each task can be undertaken in one among a set of predefined alternative modes, where each mode specifies a required set of dedicated processors and a processing time. At any time each processor can be used by a single task at most. General precedence constraints exist among tasks, and task preemption is not allowed. The problem consists of assigning a mode and a starting time to each task, respecting processor and precedence constraints, to minimize the time required to complete all tasks. The problem is NP-hard in several particular cases. In previous works, we studied algorithms in which a solution was obtained by means of an iterative procedure that combines mode assignment and sequencing phases separately. In this paper, we present some new heuristics where the decision on the mode assignment is taken on the basis of a partial schedule. Then, for each task, the mode selection and the starting time are chosen simultaneously considering the current processor usage. Different lower bounds are derived from a mathematical formulation of the problem and from a graph representation of a particular relaxed version of the problem. Heuristic solutions and lower bounds are evaluated on randomly generated test problems. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 893–911, 1999     

Two exact algorithms for the vehicle routing problem on trees

This article describes a heuristic and two exact algorithms for several classes of vehicle routing problems defined on tree networks. These include capacitated and time‐constrained vehicle routing problems. One of the exact algorithms is based on the computation of bin packing lower bounds. The other uses column generation. The first algorithm performs better on problems containing small customer demands and in which all vehicles are identical. Otherwise, the second algorithm is more powerful and more versatile. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 75–89, 1999     

针对不同视场辅助信标的无人机目标定位方法

针对无人机在单站测角测距的目标定位过程中受无人机姿态角误差影响较大的问题,提出一种对辅助信标进行探测并与惯性传感器相结合的无人机姿态求解方法。建立基于容积卡尔曼滤波的惯性传感器姿态求解模型,采用梯度下降法对基于辅助信标的无人机位姿参数进行求解,并综合它们的结果对无人机的姿态偏差进行估计和校正,最后完成了不同视场条件下的目标定位和仿真计算。结果表明,所提方法对无人机目标定位精度有明显提高。     

星箭分离相对位姿摄影测量方法

提出一种基于视觉的星箭分离相对位姿测量方法。在相机内参数已知的情况下,将相机安装于运载火箭,并在卫星上固连不少于6个合作标志,利用相机对合作标志实时成像;基于单目位姿估计的基本原理,采用高效n点渗透与正交迭代结合的方式解算卫星与火箭之间的相对位姿关系。仿真实验结果、半实物仿真实验结果证明了所提测量方法的可行性和准确性。     

Aggregating courier deliveries

We consider the problem of efficiently scheduling deliveries by an uncapacitated courier from a central location under online arrivals. We consider both adversary‐controlled and Poisson arrival processes. In the adversarial setting we provide a randomized (3βΔ/2δ ? 1) ‐competitive algorithm, where β is the approximation ratio of the traveling salesman problem, δ is the minimum distance between the central location and any customer, and Δ is the length of the optimal traveling salesman tour overall customer locations and the central location. We provide instances showing that this analysis is tight. We also prove a 1 + 0.271Δ/δ lower‐bound on the competitive ratio of any algorithm in this setting. In the Poisson setting, we relax our assumption of deterministic travel times by assuming that travel times are distributed with a mean equal to the excursion length. We prove that optimal policies in this setting follow a threshold structure and describe this structure. For the half‐line metric space we bound the performance of the randomized algorithm in the Poisson setting, and show through numerical experiments that the performance of the algorithm is often much better than this bound.     

二部图的(g,f)匹配

本文证明了二部图存在(g,f)匹配和f 因子的充要条件以及有关的几个结果,并且给出了求二部图的最大(g,f)匹配、最小(g,f)匹配和最小权最大f 匹配、最小权(g,f)匹配、最大权(g,f)匹配的算法。     

Novel approach for active vibration control of a flexible missile

This paper investigates the feasibility of using an active dynamic vibration absorber (ADVA) for active vibration control of a flexible missile system through simulation. Based on the principles of a dynamic vibration absorber (DVA), a ring-type ADVA is first designed to attenuate the elastic vibration of the flexible missile, and the design of the active controller adopts the proportional-integral-derivative (PID) control algorithm. The motion equations of a flexible missile with an ADVA, which is subjected to follower thrust at its aft end, are derived using the Lagrangian approach. Taking the minimum of the root mean square (RMS) of the lateral displacement response of the center of mass as the objective function, a genetic algorithm (GA) is used to optimize the parameter of the DVA and PID controller. The numerical calculations show that the ADVA and DVA are effective in suppressing the vibration and provide approximately 41.2% and 17.6% improvement, respectively, compared with the case of no DVA. The ADVA has better performance than the DVA. When the missile is subjected to follower thrust, the effect of vibration reduction is more effective than the case without follower thrust. It is feasible to reduce vibration and improve the stability of flexible missiles by means of the ADVA.     

捷联惯导位置更新中的多子样算法

以地理坐标系作为导航坐标系,推导了捷联惯导位置更新中的位置增量算法;提出了基于曲线拟合的多子样(二、三、四子样)涡卷补偿算法和位置旋转补偿算法.仿真结果表明,二、三、四子样涡卷补偿算法和位置旋转补偿算法都能有效地计算出涡卷补偿和位置旋转补偿值,并且二、三、四子样涡卷补偿算法和位置旋转补偿算法的精度依次提高.     

基于PMC模型的神经网络

在计算机系统中有许多诊断算法,其中针对PMC模型有0-1规划的诊断算法,这个诊断算法是NP完全的,是在多项式时间内不可解的。然而利用神经网络的高度并行性这个特点,就可以在很短的时间内解出结果。主要分析了系统诊断模型PMC的症候特征,得到其充要条件,提出了新的算法,该算法具有高度的并行性,神经网络的发展为此提供了用模拟电路来实现算法的可能性,并进行了模拟验证。     

联合作战目标协同模型构建与求解方法?

在对联合作战目标协同研究内容分析的基础上,提出了多任务部队与多作战目标的协同目标分配模型,其融合了目标综合价值、目标打击有效性、目标威胁适配度、目标类型匹配、目标距离匹配等因素。通过对各因素量化并将协同目标分配模型转换为指派问题进行求解,验证了分析方法的可行性。