几种带补偿功能的三光纤传感器的分析

在单光纤对光耦合模型的基础上 ,研究了三种带补偿功能的三光纤反射式位移传感器 ,建立了通用的光耦合的数学模型。仿真研究了它们的位移特性 ,并比较了它们的优缺点。研究结果表明 ,采用三光纤的光纤位移传感器不但线性范围、位移灵敏度和线性度等特性得到较好改善 ,而且可以有效地消除光源功率波动和反射面的反射率变化等因素对位移测量的影响     

一种强度补偿反射式光纤位移传感器的研究

:提出一种等间距排列的三探头反射式光纤位移传感器 ,该传感器通过双路接收的方法来实现光强补偿。从理论上对该种传感器的补偿机理作了详细的分析 ,得出了位移特性调制函数的表达式 ,给出了仿真曲线。结果表明 ,这种光纤传感器可以有效地消除因光源光强波动、表面反射率以及光纤传输损耗的改变对输出特性的影响     

光纤布拉格光栅的光学特性及其应用

介绍了光纤布拉格(Bragg)光栅的种类和制作,用耦合波理论分析了其基本的光反射性质,包括峰值反射率和反射半高全宽度,结果表明光纤Bragg光栅拥有独特的光反射特性.同时对光纤Bragg光栅在光纤通信、光纤传感器、滤波器等方面的应用进行了介绍和展望,表明光纤Bragg光栅将对整个光纤技术领域产生重要影响.     

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.     

复合材料单面胶接修复含中心裂纹铝合金板的疲劳特性分析

利用ANSYS有限元分析软件,建立了复合材料单面胶接修复铝合金裂纹板的裂纹长度参数化的有限元模型,分析了修复结构的裂纹尖端应力强度因子及其变化幅值的规律;与试验测试结果相结合,得到了描述修复结构疲劳特性的Paris公式材料常数;碳纤维、玻璃纤维复合材料胶接修复铝合金裂纹板的材料常数C、m分别为6.76×10-10、2.27和7.89×10-10、2.33。     

解析美国大学TESL硕士培养的主要课程与设置理据——以曼卡托明尼苏达州立大学为例

把英语作为第二语言的教学是20世纪60年代在美国兴起并逐步走向独立的科目,它在综合相关专业的同时正在朝专业化方向发展。近年来其硕士层面的教育为全球培养了大量合格的中小学英语教师,取得了较好的成绩。本文以曼卡托明尼苏达州立大学英语系为例,并结合笔者在该系攻读TESL硕士学位时的经历,解析其主要课程及设置理据。     

分层土中桩筏基础荷载分担

结合一个桩筏联合基础的设计过程,探讨了在复杂地基土上基础设计中的受力分析及变形协调计算过程.介绍了在满足复合地基承载力和变形要求前提下合理布置桩筏联合基础的做法及其设计思路.布置桩筏联合基础时使桩筏分别落在不同土层上,以充分利用不同深度地基土的承载力;另外针对桩下为非淤泥系硬土层,应最大限度利用桩身强度和天然地基承载力.该做法可以取得很好的经济效益,可供工程设计人员参考.     

Parallel machine scheduling with eligibility constraints: A composite dispatching rule to minimize total weighted tardiness

We study a parallel machine scheduling problem, where a job j can only be processed on a specific subset of machines M_j, and the M_j subsets of the n jobs are nested. We develop a two‐phase heuristic for minimizing the total weighted tardiness subject to the machine eligibility constraints. In the first phase, we compute the factors and statistics that characterize a problem instance. In the second phase, we propose a new composite dispatching rule, the Apparent Tardiness Cost with Flexibility considerations (ATCF) rule, which is governed by several scaling parameters of which the values are determined by the factors obtained in the first phase. The ATCF rule is a generalization of the well‐known ATC rule which is very widely used in practice. We further discuss how to improve the dispatching rule using some simple but powerful properties without requiring additional computation time, and the improvement is quite satisfactory. We apply the Sequential Uniform Design Method to design our experiments and conduct an extensive computational study, and we perform tests on the performance of the ATCF rule using a real data set from a large hospital in China. We further compare its performance with that of the classical ATC rule. We also compare the schedules improved by the ATCF rule with what we believe are Near Optimal schedules generated by a general search procedure. The computational results show that especially with a low due date tightness, the ATCF rule performs significantly better than the well‐known ATC rule generating much improved schedules that are close to the Near Optimal schedules. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 249–267, 2017