正弦波型直流无刷电动机位置伺服系统的变结构控制

在分析正弦波型直流无刷电动机数学模型的基础上,采用比例等速变速控制策略(PCV)设计控制器,应用于正弦波型直流无刷电动机位置伺服系统.仿真结果表明:与传统PI控制器比较,PCV控制策略可以明显改善系统的品质,并增强系统的鲁棒性.     

紧固件拆装时间预计模型

紧固件拆装作业时间是影响机械产品维修性的主要因素之一,占机械产品维修作业时间的70％～80％。因此,探讨紧固件拆装作业时间的预计方法,对研究、设计机械产品的维修性,将是十分必要的。通过分析紧固件拆装作业过程,探索出了影响拆装作业时间的诸因素,并对所有的影响因素进行分析、权衡和回归,建立紧固件拆装作业时间的预计模型。将此模型在某型履带式车辆上进行了实际验证,证明了模型的正确性及通用性。     

空空导弹导引头角预定精度研究

空空导弹导引头角预定是重要的导弹发射控制参数,其有效的计算精度分析,是导弹可靠截获和跟踪目标的重要保证。基于前置追踪攻击原理,给出了空空导弹导引头角预定的计算模型,建立了机载雷达误差对导引头角预定精度影响的误差分析仿真结构,并对仿真计算结果进行了讨论。     

具有规范化的四元数递推计算的公式误差估计

对捷联式制导系统中目前常用的四元数递推公式进行误差估计,给出利用观测数据计算四元数的误差界的公式,还介绍了保持四元数范数不变的一类递推公式。     

带减振器机抖激光陀螺惯性测量单元标定方法研究

由于减振器会产生形变,使得带减振器的机抖激光陀螺惯性测量单元(IMU)不能使用由精密转台提供姿态基准的标定方法进行标定.提出了一种带减振器的机抖激光陀螺IMU标定的新方法,该方法先将IMU固联在精密转台上,不启动陀螺,依靠转台提供姿态参考标定出加表各误差参数;在此基础上装上减振器,设计了IMU陀螺误差参数标定路径,根据...     

速率偏频激光陀螺寻北仪中转台测角周期性误差的影响分析

连续旋转式寻北仪以其突出的性能成为当前寻北仪研究的热点,但关于转台误差对连续旋转寻北算法精度影响的分析很少.针对速率偏频激光陀螺寻北仪,研究了转台测角周期性误差对寻北结果的影响.理论分析表明,测角周期性误差的存在会导致寻北结果偏离真实值,必须对其进行建模和补偿以提高寻北精度.对理论分析结果进行了仿真实验和样机寻北实验验...     

Batch scheduling on a two‐machine jobshop with machine‐dependent setup times

The problem of minimum makespan on an m machine jobshop with unit execution time (UET) jobs (m ≥ 3) is known to be strongly NP‐hard even with no setup times. We focus in this article on the two‐machine case. We assume UET jobs and consider batching with batch availability and machine‐dependent setup times. We introduce an efficient \begin{align*}(O(\sqrt{n}))\end{align*} algorithm, where n is the number of jobs. We then introduce a heuristic for the multimachine case and demonstrate its efficiency for two interesting instances. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

Periodic review inventory management with contingent use of two freight modes with fixed costs

We study a stochastic inventory model of a firm that periodically orders a product from a make‐to‐order manufacturer. Orders can be shipped by a combination of two freight modes that differ in lead‐times and costs, although orders are not allowed to cross. Placing an order as well as each use of each freight mode has a fixed and a quantity proportional cost. The decision of how to allocate units between the two freight modes utilizes information about demand during the completion of manufacturing. We derive the optimal freight mode allocation policy, and show that the optimal policy for placing orders is not an (s,S) policy in general. We provide tight bounds for the optimal policy that can be calculated by solving single period problems. Our analysis enables insights into the structure of the optimal policy specifying the conditions under which it simplifies to an (s,S) policy. We characterize the best (s,S) policy for our model, and through extensive numerical investigation show that its performance is comparable with the optimal policy in most cases. Our numerical study also sheds light on the benefits of the dual freight model over the single freight models. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

基于聚类算法的多无人机系统任务分配

针对现有任务分配方法在任务点较多时不易解算,且计算量大的问题,提出了基于模糊C-均值聚类算法的多无人机系统任务分配方法.首先,利用模糊C-均值聚类算法得到的隶属度矩阵对任务点进行初始分配;其次,针对基于空间划分聚类可能造成各UAV任务不均衡的问题,设计任务的局部优化调整规则;最后,结合单旅行商问题,利用Tabu Sea...     

Quantifying the performance effects of idle time utilization in multiserver systems

In many practical multiserver queueing systems, servers not only serve randomly arriving customers but also work on the secondary jobs with infinite backlog during their idle time. In this paper, we propose a c‐server model with a two‐threshold policy, denoted by (e d), to evaluate the performance of this class of systems. With such a policy, when the number of idle servers has reached d (<c), then e (<d) idle agents will process secondary jobs. These e servers keep working on the secondary jobs until they find waiting customers exist in the system at a secondary job completion instant. Using the matrix analytic method, we obtain the stationary performance measures for evaluating different (e, d) policies. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007.