基于 EEMD 的滚动轴承故障诊断方法

针对经验模态分解（empirical mode decomposition,EMD）方法处理轴承振动信号时存在的缺点,指出极值点的选择是产生模态混叠现象的原因。分析了集成经验模态分解（ensemble empirical mode decomposi-tion,EEMD）方法抑制模态混叠现象的原理,讨论了加入高斯白噪声的次数和大小对 EEMD 方法分解结果的影响,并通过仿真和实测信号对 EMD 和 EEMD 方法的性能进行了比较测试。结果表明：EEMD 方法不仅能够有效地抑制模态混叠现象,而且能更好地反映出轴承振动信号中的故障信息。同时,对通过 EEMD 方法得到的重构信号进行平方包络分析,结果证明：该方法能够有效地提取出滚动轴承的故障特征。     

三相逆变器新型积分控制加状态反馈控制

三相逆变器在实际运行中,不平衡负载工况较为常见,原因是传统积分控制加状态反馈控制无法实现三相输出电压的对称性。针对该问题提出了不平衡负载条件下三相逆变器新型积分控制加状态反馈控制策略,并通过仿真和实验验证了该策略能有效降低不平衡负载时三相逆变器输出电压的不平衡度,从而获得对称的三相输出电压波形。     

钢质管道挤压变形实验研究与结果分析

野外埋地敷设的长距离输油管道发生断裂等较大破坏时,采用管道局部挤压的方式,在较短时间内将管道快速压扁以截断流油。为了设计管道挤压截流装置,使用18 mm宽度的压头对?325 mm×6 mm的X60钢管进行挤压变形实验,得到了管道挤压的载荷-位移曲线、管道的变形范围、管道压扁后的回弹情况和挤压过程中的塑性载荷等数据,并验证了管道挤压过程中的安全性。通过实验,不仅可以研究管道塑性破坏后的变形规律,而且为管道泄漏抢修提供了理论和实践参考。     

径向载荷作用下管道挤压变形过程数值模拟

野外埋地敷设的长距离输油管道发生断裂等较大事故时,采用管道局部挤压的方式可以在较短时间内将管道快速压扁以截断流油。为设计管道挤压截流装置,运用ANSYS Workbench建立上下压头加载作用下管道挤压的有限元模型,完成对ф159 mm×5 mm的45号钢挤压变形模拟仿真,得到管道挤压的等效应力、位移分布、变形范围和载荷-位移曲线等。将模拟数据与实验数据进行对比,两者结果比较吻合,可以为管道泄漏抢修提供理论和实践参考。     

基于来袭鱼雷方位变化率的制导类型识别技术

对来袭鱼雷的制导类型进行识别是水面舰艇实施有针对性鱼雷防御的前提条件,方位变化率则可作为类型识别的一个重要的识别依据。首先,从不同类型潜射鱼雷的发射方式和弹道特征入手,分别推导出潜射直航鱼雷、声自导鱼雷、尾流自导鱼雷方位变化率的表达式。其次,仿真分析了不同类型潜射鱼雷方位变化率的影响因素。最后,在给定的态势下,给出了四种不同类型潜射鱼雷方位变化率随雷舰距离的变化规律曲线。仿真结果能为鱼雷制导类型识别提供一定的参考依据。     

Should competing firms reveal their capacity?

In this article, we explore when firms have an incentive to hide (or reveal) their capacity information. We consider two firms that aim to maximize profits over time and face limited capacity. One or both of the firms have private information on their own capacity levels, and they update their beliefs about their rival's capacity based on their observation of the other firm's output. We focus on credible revelation mechanisms—a firm may signal its capacity through overproduction, compared to its myopic production levels. We characterize conditions when high‐capacity firms may have the incentive and capability to signal their capacity levels by overproduction. We show that prior beliefs about capacity play a crucial, and surprisingly complex, role on whether the firm would prefer to reveal its capacity or not. A surprising result is that, despite the fact that it may be best for the high‐capacity firm to overproduce to reveal its capacity when capacity information is private, it may end up with more profits than if all capacity information were public knowledge in the first place. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

基于证据理论的军械装备修理能力认证评估方法

借鉴AHP法建立军械装备修理能力认证评估体系,并构建其递阶层次模型。确立体系各级指标权重中,引入D-S证据理论对多专家意见进行融合;综合考虑专家的权重和不确定度,并采用单值转换分布概率算法对专家评价分数进行换算,改进了AHP法受专家经验、知识限制,主观性强等缺点。经算例分析,该方法能准确可靠地评价型号装备修理机构的修理能力,减少专家主观因素对评估结果的影响。     

遵循人体生物规律提高部队中长跑训练水平

中长跑训练是部队训练的重要内容,训练中要防止过度负荷,重视无氧代谢能力提高,遵循身体训练的周期节律,从而有效提高训练效率,保证训练的科学化。     

潜艇不机动纯方位解算编队目标运动要素方法

针对单艘潜艇纯方位目标定位必须潜艇机动才能使算法收敛的问题,首次采用几何分析法研究了潜艇不机动情况下,解算编队目标运动要素的方法;然后,基于最小二乘法,给出了具体的解算模型,并给定态势,进行实例仿真。证明该算法能够满足潜艇隐蔽对编队目标定位的需要,进一步丰富了潜艇纯方位目标定位方法。     

A generalized assignment model for dynamic supply chain capacity planning

We consider a generalization of the well‐known generalized assignment problem (GAP) over discrete time periods encompassed within a finite planning horizon. The resulting model, MultiGAP, addresses the assignment of tasks to agents within each time period, with the attendant single‐period assignment costs and agent‐capacity constraint requirements, in conjunction with transition costs arising between any two consecutive periods in which a task is reassigned to a different agent. As is the case for its single‐period antecedent, MultiGAP offers a robust tool for modeling a wide range of capacity planning problems occurring within supply chain management. We provide two formulations for MultiGAP and establish that the second (alternative) formulation provides a tighter bound. We define a Lagrangian relaxation‐based heuristic as well as a branch‐and‐bound algorithm for MultiGAP. Computational experience with the heuristic and branch‐and‐bound algorithm on over 2500 test problems is reported. The Lagrangian heuristic consistently generates high‐quality and in many cases near‐optimal solutions. The branch‐and‐bound algorithm is also seen to constitute an effective means for solving to optimality MultiGAP problems of reasonable size. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012