变工况下轴承健康监测的相关向量机与自适应阈值模型方法

工况在旋转机械运行过程中通常是变化的。变化的工况和故障一样,也会引起机械振动特征发生改变,从而引起诊断误差。为此,提出一种用于变工况下轴承健康监测的新方法。该方法使用相关向量机拟合振动特征的统计量随工况参数的变化,得到特征统计量与工况参数之间的连续函数关系;基于不同工况下的特征统计,构建自适应阈值模型。将该方法用于不同转速下的轴承健康监测,结果表明,当转速超过某一个较小的值时,该方法有效。     

基于恒虚警的多卫星信号快速盲检测算法?

在分析实际盲卫星通信信号的基础上,提出了一种对不重叠多卫星信号数量、中心频率进行实时估计的快速盲检测算法。算法基于恒虚警率准确地估计了噪声的统计特性进而设置了信噪分离的门限,并根据卫星通信信号的实际带宽特性实现了盲信号的检测。仿真结果表明,算法能够在较低的信噪比下实现对多卫星信号的快速准确盲检测,且与其他算法相比,该算法准确率高、通用性强,更能满足实际工程的需要。     

A sequential auction‐bargaining procurement model

One of the most important decisions that a firm faces in managing its supply chain is a procurement decision: selecting suitable suppliers among many potential competing sellers and reducing the purchase cost. While both auctions and bargaining have been extensively studied in the literature, the research that combines auctions and bargaining is limited. In this article, we consider a combined auction‐bargaining model in a setting where a single buyer procures an indivisible good from one of many competing sellers. The procurement model that we analyze is a sequential model consisting of the auction phase followed by the bargaining phase. In the auction phase, the sellers submit bids, and the seller with the lowest bid is selected as the winning bidder. In the bargaining phase, the buyer audits the cost of the winning seller and then negotiates with him to determine the final price. For this auction‐bargaining model, we find a symmetric equilibrium bidding strategy for the sellers in a closed form, which is simple to understand and closely related to the classical results in the auction and bargaining literature. We also show that the auction‐bargaining model generates at least as much profit to the buyer as the standard auction or sequential bargaining model. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

有源干扰条件下防空导弹单发命中概率统计模型

分析了典型有源干扰对地空导弹防空各个过程的干扰方式和作用机理,建立了一种地空导弹射击有电子掩护的目标的单发命中概率统计模型．     

Threshold optimization for weighted voting classifiers

Weighted voting classifiers considered in this paper consist of N units each providing individual classification decisions. The entire system output is based on tallying the weighted votes for each decision and choosing the one which has total support weight exceeding a certain threshold. Each individual unit may abstain from voting. The entire system may also abstain from voting if no decision support weight exceeds the threshold. Existing methods of evaluating the reliability of weighted voting systems can be applied to limited special cases of these systems and impose some restrictions on their parameters. In this paper a universal generating function method is suggested which allows the reliability of weighted voting classifiers to be exactly evaluated without imposing constraints on unit weights. Based on this method, the classifier reliability is determined as a function of a threshold factor, and a procedure is suggested for finding the threshold which minimizes the cost of damage caused by classifier failures (misclassification and abstention may have different price.) Dynamic and static threshold voting rules are considered and compared. A method of analyzing the influence of units' availability on the entire classifier reliability is suggested, and illustrative examples are presented. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 322–344, 2003.     

单洞双层隧道围岩力学特性分析

单洞双层隧道作为一种新的隧道形式,不同于分离式隧道和连拱式隧道。利用ANSYS对单洞双层隧道和分离式隧道开挖后围岩的情况进行数值模拟,分析开挖后围岩的应力和位移变化情况、塑性区分布和安全系数,通过对比得出：在浅埋情况下两种隧道围岩应力和位移分布基本一致,地表沉降和分离式隧道相当;单洞双层隧道对围岩扰动深度较大,边墙是其薄弱部位,应力松弛明显,水平位移较大,塑性区水平方向分布较大。     

模糊小波包在漏磁信号处理中的应用

采用小波包去噪方法解决漏磁信号的噪声抑制问题。针对软、硬阈值处理中存在的缺陷,提出了模糊阈值处理方法,应用该方法对采集的漏磁信号进行消噪处理。实验结果表明,与传统小波包的去噪效果相比较,模糊小波包降噪方法不仅较好地剔除信号中的噪声,而且保留了原始信号中的有效成分,是一种可行的方法。     

GPS单孔径双极化天线抗干扰算法与性能分析

设计了一种利用单孔径双极化天线进行GPS自适应抗干扰的方法,并对算法的性能进行了详细的分析.新方法在不降低卫星信号质量的前提下,仅占用单个天线位置,就可以对付窄带或宽带干扰,为增强安装受限装备的导航抗干扰能力提供了一种新的解决方案.仿真结果表明,新方法可行、有效.     

机载雷达功能仿真中地球曲率的影响

从机载雷达目标探测过程出发,构建目标回波的单程增益系数和地表漫反射的后向散射系数的数学模型,根据此模型提出机载雷达的相应性能指标.在仿真实验的基础上,分析了地球曲率对目标回波和面杂波功率的影响.仿真结果表明了该模型的正确性和有效性.     

单站测向定位技术研究

对单站测向定位的技术进行了研究,结果表明:固定单站测向定位只能确定目标运动的航向,并给出了航向的计算方法;运动平台单站测向定位可以确定目标运动的航迹(测向平台以匀速直线运动除外),给出了目标位置的计算方法;同时探究了运动平台做匀速直线运动不能对目标定位的原因,进一步明确了运动平台单站测向定位的条件.