基于三站点库存组织的备件转运策略分析

基于三站点库存组织研究了备件转运策略对于系统期望延期交货量（EBO）的影响。首先,依据三站点库存组织中备件和故障件的消耗与补给过程以及库存控制策略,给出了考虑保障站点供应优先级的手边现货、应得备件数和延期交货量之间的状态方程。其次,通过定义站点延期交货量与应得备件数之间的比例系数,将原非线性方程组转化成线性方程组,然后借助线性方程组解的判定法则对方程组解的唯一性进行判定,并结合不动点原理构造柯西列逼近原方程的解。最后,在算例分析中借助MATLAB对2种转运策略（按固定概率转运和按优先级约束转运）下系统EBO的数值大小进行对比。结果表明:按优先级约束进行备件转运能够在大部分情况下提高备件利用率同时降低系统EBO。此外,通过分析还可以发现,不同备件转运策略对系统EBO作用效果的显著性主要由转运策略的可行作用空间大小决定,而作用空间的可行变化范围主要由备件需求由本地满足的概率、库存配置方案以及需求率和维修速率决定。      

运用双重环境模型的移动机器人主动探测策略

针对移动机器人基于超声波传感器的地图创建,提出了一种双重环境模型。该模型同时包涵以直线段表示的几何模型和以概率形式表示的栅格模型,结合了几何模型与栅格模型的优点。给出了该模型的建立及更新算法,并基于该模型提出了一种主动探测策略,在保证探测效率的同时减小了超声波传感器的镜面反射产生的不良影响。在室内环境下进行移动机器人实验,验证了基于双重环境模型的探测策略的有效性。     

三维型面非接触测量系统现场标定技术

针对双眼视觉传感器三维型面测量系统,介绍了一种利用平面标靶实现系统标定的方法.标定过程无需辅助设备,仅要求两个摄像机同时拍摄一幅标定板图像,利用标定板上的控制点计算左右图像对应的单应性矩阵.结合进化策略优化左右主像点,从单应性矩阵中获得测量系统的其他标定参数.同传统定标方法相比,该方法简单、快捷,适用于现场标定.      

拓扑自动发现中数据更新策略的研究

首先提出了在拓扑发现数据更新中的若干实际问题,然后对这些问题一一给出了解决方案,并提出一种基于状态的拓扑发现更新策略.最后,通过在一个比较大的局域网中的试验,在正确性和效率方面对该策略的性能进行了评价.      

一种数据链用户保障策略研究与设计

针对数据链性能质量和服价问题,提出一种基于可靠性理论的数据链用户冗余策略,并建立 数学模型.模型综合平衡了冗余运行和正常维护的关系,从而大大改进了系统的性能.模型采 用一定的状态检查和验证策略,有效保证网络的正常工作.设备之间各自独立,相互协作, 合作完成容错任务.该模型与特定的系统应用环境无关,提供了一个通用的容错系统框架, 并给出实例说明其计算方法.      

A novel visual attention method for target detection from SAR images

Synthetic Aperture Radar(SAR) imaging systems have been widely used in civil and military fields due to their all-weather and all-day abilities and various other advantages. However, due to image data exponentially increasing, there is a need for novel automatic target detection and recognition technologies. In recent years, the visual attention mechanism in the visual system has helped humans effectively deal with complex visual signals. In particular, biologically inspired top-down attention models have garnered much attention recently. This paper presents a visual attention model for SAR target detection, comprising a bottom-up stage and top-down process.In the bottom-up step, the Itti model is improved based on the difference between SAR and optical images. The top-down step fully utilizes prior information to further detect targets. Extensive detection experiments carried out on the benchmark Moving and Stationary Target Acquisition and Recognition(MSTAR) dataset show that, compared with typical visual models and other popular detection methods, our model has increased ability and robustness for SAR target detection, under a range of Signal to Clutter Ratio(SCR) conditions and scenes. In addition, results obtained using only the bottom-up stage are inferior to those of the proposed method, further demonstrating the effectiveness and rationality of a top-down strategy. In summary, our proposed visual attention method can be considered a potential benchmark resource for the SAR research community.     

An aero-engine life-cycle maintenance policy optimization algorithm: Reinforcement learning approach

An aero-engine maintenance policy plays a crucial role in reasonably reducing maintenance cost. An aero-engine is a type of complex equipment with long service-life. In engineering,a hybrid maintenance strategy is adopted to improve the aero-engine operational reliability. Thus,the long service-life and the hybrid maintenance strategy should be considered synchronously in aero-engine maintenance policy optimization. This paper proposes an aero-engine life-cycle maintenance policy optimization algorithm that synchronously considers the long service-life and the hybrid maintenance strategy. The reinforcement learning approach was adopted to illustrate the optimization framework, in which maintenance policy optimization was formulated as a Markov decision process. In the reinforcement learning framework, the Gauss–Seidel value iteration algorithm was adopted to optimize the maintenance policy. Compared with traditional aero-engine maintenance policy optimization methods, the long service-life and the hybrid maintenance strategy could be addressed synchronously by the proposed algorithm. Two numerical experiments and algorithm analyses were performed to illustrate the optimization algorithm in detail.     

基于MDO策略的民用航空发动机概念设计研究

以某型民用涡扇航空发动机概念设计为例,集成了总体方案（包括热力循环分析、质量评估、噪声评估、氮氧化物排放评估）、风扇（包括气动设计、强度分析）、低压涡轮（包括气动设计、强度分析）3个子系统,以设计点耗油率、整机质量、飞越状态总声功率级、进近状态总声功率级和燃烧室氮氧化物排放量为优化目标,进行了基于多目标的整机多学科设计优化（MDO）的研究。对比研究了单学科可行(IDF)、协作优化(CO)和不对称子空间优化 (ASO)3种典型的优化策略及其在整机MDO中的应用,探讨了整机 MDO的建模方法、子系统间数据传递及解耦方式。结果表明:3种策略优化效率相当,优化时间最大相差742s;CO策略与ASO策略在整机MDO应用中优化效果较好,综合评价指标分别降低了0.82%和0.86%。      

永磁同步电机弱磁与过调制控制策略研究

在前人研究的基础上,提出了一种提升永磁同步电机(PMSM)高速带载能力的控制策略。该控制策略能克服电机在最高转速时无法带载的弱点,可靠性高、易于实现。实现该控制策略的算法包含PMSM的弱磁控制和电压空间矢量的过调制控制,使电机能宽范围带载调速。为验证该控制策略,建立了内置式永磁同步电机(IPMSM)的仿真模型,搭建了试验平台,并进行了仿真和试验研究,验证了该控制策略的可行性和有效性。     

非结构弹性体动网格方法应用策略及改进

针对3种代表性的经典弹性体动网格方法,从网格最大变形能力、质量评价指标和空间分布趋势3个方面综合分析了各方法的网格变形特性,重点总结了各方法的适用范围.结合工程实际,研究了特定问题的弹性体动网格应用策略.最后,整合各经典弹性体动网格方法的优势提出了改进方法,并通过NACA 0006翼型的超声速俯仰振荡加以验证.研究结果表明:基于面积的弹性体法适用于加密型网格,而基于距离的弹性体法适用于均匀型网格,该应用策略可为工程问题提供指导.改进方法效果明显,在大变形时相对基于距离的弹性体法的各项网格质量增幅均在10%以上,相对基于面积的弹性体法的最小网格质量增幅几乎达到4倍,并且在数值模拟中具有较高的精度,可显著增强弹性体法的鲁棒性.