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Variation reduction of manufacturing processes is an essential objective of process quality improvement. It is highly desirable to develop a methodology of variation source identification that helps quickly identify the variation sources, hence leading to quality improvement and cost reduction in manufacturing systems. This paper presents a variation source identification method based on the analysis of the covariance matrix of process quality measurements. The identification procedure utilizes the fact that the eigenspace of the quality measurement covariance matrix can be decomposed into a subspace due to variation sources and a subspace purely due to system noise. The former subspaces for different samples will be the same if the same variation sources dominate. A testing procedure is presented, which can determine the closeness of the subspaces under sampling uncertainty. A case study is conducted to illustrate the effectiveness of this methodology. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006. 相似文献
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用C++Builder强有力的控件技术及多线程技术,实现一个32位串口控件,并将其应用于串行设备软件接口,走出传统的由动态链接库提供低层接口软件的方式,从而大大减轻上层应用软件的开发负担 相似文献
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选取其关键部件—喷口加力调节器作为故障诊断研究对象,提出了一种基于动态主元分析(DPCA)和广义回归神经网络(GRNN)相结合的喷口加力调节器故障诊断方法。在燃气轮机专用试验平台对其进行试验,采集喷口加力调节器的高压转子转速、低压转子转速、燃油油量、燃油耗量等参数原始数据,对其进行预处理,并采用DPCA方法对其进行动态主元分析,提取其不同健康状态的主元,构建特征向量,采用特征向量构建GRNN神经网络故障诊断模型,并通过测试数据对该方法的有效性进行试验验证。为表明该方法的有效性,采用了基于GRNN和基于DPCA-RBF的方法对喷口加力调节器不同健康状态进行了诊断技术研究,并对不同方法所得到的诊断结果进行了对比分析。结果表明,采用DPCA和GRNN相结合的故障诊断方法能有效识别出喷口加力调节器不同的健康状态,具有很好的实际应用价值。 相似文献
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王双喜 《军械工程学院学报》1998,(3)
某军品的黄铜锻件在生产过程中产生了一种凹坑腐蚀缺陷。用金相方法对其显微组织进行研究,确定该组织缺陷由外氧化皮、内氧化区和脱锌带三部分组成,得出产生该缺陷的根本原因在于锻件酸洗时造成了缝隙腐蚀。 相似文献
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设G是简单连通图,r_n~c(G)和ir_n(G)分别表示图G的连通n-Domination数和n-Irredundance数、本文证明了如下结论:r_n~c(G)≤(3n+1)ir_n(G)-2n。 相似文献
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Consider a binary, monotone system of n components. The assessment of the parameter vector, θ, of the joint distribution of the lifetimes of the components and hence of the reliability of the system is often difficult due to scarcity of data. It is therefore important to make use of all information in an efficient way. For instance, prior knowledge is often of importance and can indeed conveniently be incorporated by the Bayesian approach. It may also be important to continuously extract information from a system currently in operation. This may be useful both for decisions concerning the system in operation as well as for decisions improving the components or changing the design of similar new systems. As in Meilijson [12], life‐monitoring of some components and conditional life‐monitoring of some others is considered. In addition to data arising from this monitoring scheme, so‐called autopsy data are observed, if not censored. The probabilistic structure underlying this kind of data is described, and basic likelihood formulae are arrived at. A thorough discussion of an important aspect of this probabilistic structure, the inspection strategy, is given. Based on a version of this strategy a procedure for preventive system maintenance is developed and a detailed application to a network system presented. All the way a Bayesian approach to estimation of θ is applied. For the special case where components are conditionally independent given θ with exponentially distributed lifetimes it is shown that the weighted sum of products of generalized gamma distributions, as introduced in Gåsemyr and Natvig [7], is the conjugate prior for θ. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 551–577, 2001. 相似文献
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运用逐步回归和主成分分析的方法,选取了装甲车辆诸多战技性能指标集合中的自变量子集,建立了该子集与使用与保障费用之间指数回归方程组.该模型也可推广应用于装甲车辆综合性能的评估. 相似文献
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