预应力作用超磁致伸缩材料磁滞回线的温度敏感性分析

超磁致伸缩材料Terfenol-D具有应力温度敏感特性。通过循环油浴加热的实验方法,测量超磁致伸缩材料在力热磁耦合下的磁滞回线,发现预应力的增加有效降低了温度对材料低磁场性能的影响,材料显示了良好的低磁场温度稳定性能。试件在高预应力120 MPa、磁场强度300 kA/m的条件,磁化强度出现先增大后减小的现象,磁化衰减幅度得到减弱。     

Optimal inventory control policy for periodic‐review inventory systems with inventory‐level‐dependent demand

We consider a setting in which inventory plays both promotional and service roles; that is, higher inventories not only improve service levels but also stimulate demand by serving as a promotional tool (e.g., as the result of advertising effect by the enhanced product visibility). Specifically, we study the periodic‐review inventory systems in which the demand in each period is uncertain but increases with the inventory level. We investigate the multiperiod model with normal and expediting orders in each period, that is, any shortage will be met through emergency replenishment. Such a model takes the lost sales model as a special case. For the cases without and with fixed order costs, the optimal inventory replenishment policy is shown to be of the base‐stock type and of the (s,S) type, respectively. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

Monitoring the market or the salesperson? The value of information in a multilayer supply chain

We study a supply chain in which a manufacturer relies on a salesperson to sell the products to the consumers. The sales outcome is determined by a random market condition and the salesperson's service level, both of which are privately observed by the salesperson. Apart from them, there are two types of resellers: a knowledgeable reseller observes the market condition, whereas a diligent reseller can monitor the service level. While delegating to a reseller enhances information acquisition, it may also result in double marginalization and inefficiency. We identify several operating regimes in which double marginalization can be eliminated via simple contracts and establish the benefit of monitoring the salesperson over monitoring the market. Our dominance result is not prone to our model characteristics regarding the complementarity of market condition and sales effort, the relative importance of adverse selection and moral hazard, and the contract form. We then generalize our model and re‐establish the dominance result in the presence of reseller's risk aversion or private monitoring expertise. We also quantify the performance gaps among different selling schemes under various scenarios. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

美军军官晋升的若干特点

顺应新军事变革的发展趋势,美军在实践中不断改革和创新军官的晋升工作,采取有效的形式,建立了稳定的制度,形成了系统的观点,选拔任用了一大批高素质复合型的优秀军官。美军军官晋升中反映的一些基本特点,非常值得我们去深入地研究和把握。一、法规健全美军认为,法制化是从总体上防止军官晋升随意性的重要保证,必须不断推进军官晋升的法制化进程。国会、国防部和各军种都不遗余力,制定了种类繁多、覆盖广泛、层次齐全的军官人事管理法律法规和规章制度,为军官晋升提供了客观的依据、统一的标准和科学的指导。在基本法层面上,有国会通过的《…     

基于C3D辅助的战场传感器监视系统设计与实现

首先介绍了战场传感器监视系统的定义和各国现有典型系统。其次针对战场监视特殊的应用环境,利用C3D辅助技术,将相对定位与基于三维地图环境下的绝对定位相结合,通过坐标转换和地图匹配将位置信息直观准确反映在电子地图上,设计了基于C3D辅助的战场传感器监视系统,并对该系统进行了实现。最后通过对3D-MDS(C,D)定位算法的验证结果表明,在长1000m×7m宽的道路上,布撒120个节点,对于速度为3m/s的装甲车定位误差仅为2.1687米。该系统可对定位算法的定位精度进行评测及误差进行修正,防止由于误差累积造成误差放大。     

误差配准在两种纯距离定位算法的应用比较

组网雷达系统中,由于观测信息量的增加,对目标存在多种定位算法。很多情形下,误差配准公式是基于某一定位算法推导而来,误差配准的结果也相应的用来提高此定位算法的定位精度。定位算法的复杂程度不同导致基于此算法推导误差配准公式难度不一致,不同定位算法的定位精度也不尽相同。因此,对两种多距离定位算法的定位精度、误差配准推导难易程度进行了理论分析和仿真计算,给出了定位精度的解析表达式和仿真结果。利用表达式简单的定位算法推导基于最小二乘的误差配准公式,并将误差配准结果反馈给定位精度高的定位算法,以最大程度提高误差配准结果的应用效果,减轻计算复杂度,提高信息的利用度。     

三热源热泵有限时间经济性能优化

本文用有限时间热力学与经济优化相结合的方法,导出ｑ∝△（Ｔ）和ｑ∝△（Ｔ－１）两种传热规律下,三热源热泵的最佳利润率、供热系数关系,得到最大利润率时的供热系数界限。     

磁性微粉/聚乙烯复合材料的电磁特性

研究了磁性微粉的物相组成及其与聚乙烯相复合制成的吸波材料在８． ２～１２． ４ＧＨｚ 频段内的电磁特性。结果表明： 复合材料中聚乙烯的加入量对电磁特性在上述频段内各频率范围影响程度不同； 磁性微粉中聚碳硅烷量为２０％ 时， 反射衰减大于６ｄＢ对应的频带宽度为２ＧＨｚ。     

纳米Si-C-N粒子增强Si3N4 复合材料的结构与性能

本文用Ｓｉ－Ｃ－Ｎ纳米微粉做增强相,Ｓｉ３Ｎ４微粉为基相,采用热压的方法制备了ＳｉＣｐ／Ｓｉ３Ｎ４纳米复相陶瓷,所得的ＳｉＣｐ／Ｓｉ３Ｎ４复合材料的室温弯曲强度为８７８．５ＭＰａ,断裂韧性达１１．９６ＭＰａｍ１／２,同时应用扫描电镜（ＳＥＭ）、高分辨透射电镜（ＨＲＴＥＭ）对其结构进行了观察,讨论了结构与性能之间的关系。     

多Agent系统中Agent计算的能力理论

能力是规范Ａｇｅｎｔ的一个重要抽象概念。本文提出了规划树概念以刻划在动态、不确定的多Ａ－ｇｅｎｔ系统中Ａｇｅｎｔ如何通过对其规划进行合理、有效的组织来实现其任务、维护某些条件。基于规划树概念,本文给出了能力概念的形式化语义定义,获取和描述了它的一些重要属性。