A model for preventive maintenance operations and forecasting

Equipment costs constitute the greatest majority of overall costs for semiconductor manufacturing. Therefore, maintaining high equipment availability has been regarded as one of the major goals in the industry. The ability to forecast correctly equipment preventive maintenance (PM) timing requirements not only can help optimizing equipment uptime but also minimizing negative impacts on manufacturing production efficiency. This research used grey theory and evaluation diagnosis to construct a PM forecasting model for prediction of PM timing of various machines. The results showed significant improvements of PM timing predictions compared to the existing method based on experience and an alternative method proposed by Li and Chang (Semiconductor Manufacturing Technology Workshop 2002: 10–11, pp. 275–277) for the same fab cases. Received: June 2005 / Accepted: December 2005     

盖层封闭能力的灰聚类评价方法

提出灰聚类评价方法，用于盖层封闭能力定量评价。所有被评价对象构成聚类对象集，所有评价指标构成评价指标集，所划分的盖层封闭能力等级构成聚类的灰类集，按照最大聚类权确定对象所属的灰类，即盖层的封闭能力级别。评价流程是：确定指标灰类模式→数据预处理→利用聚类公式计算→利用最大聚类权准则抉择。这种方法避免了加法评分法要依靠人的主观经验划定总评分值的问题，而且由于把评价对象视为“灰”的，具有处理边缘信息的能力。以琼东南盆地３个主要探区的盖层封闭性评价为例，介绍了灰聚类评价的具体应用方法。灰聚类评价方法同样可用于储集层评价、圈闭评价等地质问题的定量研究。表２参３（王孝陵摘     

灰色预测法在西安市农村电话预测中的应用

在对西安市农村电话发展现状分析的基础上 ,运用灰色预测法对西安市农村电话未来发展趋势进行预测 ,为制定西安市农村电话发展策略提供参考     

柴油添加剂功效影响因素的灰色关联分析

提出了一种柴油添加剂非台架实验的功效判断方法——灰色关联分析法。应用这个方法分析待测功效的柴油添加剂，可通过测定加入它后的柴油样品的物理性质和加入已知功效较好的柴油添加剂的柴油样品的物理性质，再作灰色关联分析，综合关联顺序以评定其功效好坏。应用这个方法还可推断柴油样品的表面张力是影响燃烧好坏的主要因素，其次是粘度、十六烷值和燃点。     

Efficient Legendre moment computation for grey level images

Legendre orthogonal moments have been widely used in the field of image analysis. Because their computation by a direct method is very time expensive, recent efforts have been devoted to the reduction of computational complexity. Nevertheless, the existing algorithms are mainly focused on binary images. We propose here a new fast method for computing the Legendre moments, which is not only suitable for binary images but also for grey level images. We first establish a recurrence formula of one-dimensional (1D) Legendre moments by using the recursive property of Legendre polynomials. As a result, the 1D Legendre moments of order p, L_p=L_p(0), can be expressed as a linear combination of L_p-1(1) and L_p-2(0). Based on this relationship, the 1D Legendre moments L_p(0) can thus be obtained from the arrays of L₁(a) and L₀(a), where a is an integer number less than p. To further decrease the computation complexity, an algorithm, in which no multiplication is required, is used to compute these quantities. The method is then extended to the calculation of the two-dimensional Legendre moments L_pq. We show that the proposed method is more efficient than the direct method.     

近程防御系统中多空中目标威胁度分析

研究近程防御系统,快速打击威胁目标的控制是整个系统的主要问题。针对敌方空中目标批次较多、运动状态复杂,而我方防御火力有限,对目标进行有效、精确拦截,需要对目标威胁度排序,依次进行打击。为了正确识别对整个目标过程,进行定性和定量的分析判断,提出了一种行之有效的灰色关联分析的变权威胁度分析方法;进行仿真,生成空中多组动态飞行目标,采用上述算法对空中目标有效识别,并对威胁度进行排序,进行打击。实验结果与专家评估后的结果完全一致,并能够准确而快速的在战场做出决策。     

遗传优化的GNNM在瓦斯涌出量预测中的应用

研究矿井瓦斯涌出量准确预测一直是煤矿安全生产中重点关注的问题。煤层瓦斯爆炸因受开发环境、矿层深度、天气等因素的影响,造成与瓦斯涌出量增大而引起的。针对传统预测模型在矿井瓦斯涌出量预测中存在建模困难、收敛速度慢、要求历史数据量大的问题,提出了一种遗传优化的灰色神经网络预测模型。模型利用灰色系统对数据量要求低的特点,将灰色系统理论与神经网络有机结合起来,建立灰色神经网络模型。并采用遗传算法对所建立模型的权值和阈值进行优化。采用模型对矿井瓦斯涌出量进行预测,实验表明,遗传优化的灰色神经网络模型,可以简化系统建模,并能提高瓦斯涌出量预测精度,有一定的实用价值。     

Failure mode and effects analysis using D numbers and grey relational projection method

Failure mode and effects analysis (FMEA) is a widely used risk assessment tool for defining, identifying and eliminating potential failures or problems in products, process, designs and services. Two critical issues of FMEA are the representation and handling of various types of assessments and the determination of risk priorities of failure modes. Many different approaches have been suggested to enhance the performance of traditional FMEA; however, deficiencies exist in these approaches. In this paper, based on a more effective representation of uncertain information, called D numbers, and an improved grey relational analysis method, grey relational projection (GRP), a new risk priority model is proposed for the risk evaluation in FMEA. In the proposed model, the assessment results of risk factors given by FMEA team members are expressed and modeled by D numbers. The GRP method is used to determine the risk priority order of the failure modes that have been identified. Finally, an illustrative case is provided to demonstrate the effectiveness and practicality of the proposed model.     

灰色关联分析法在矿体可崩性评价中的应用

在用软划分方法建立矿体可崩性分级标准的基础上，提出了评价矿体可崩性的灰色关联分析法，并结合实例进行了验证．     

一种基于灰色系统理论的控制系统参数辨识算法的仿真研究

灰色预测补偿是一种对灰色系统进行白化的算法,该算法需要的信息少、计算量小。它可以克服常规PID控制存在超调的缺点。根据灰色PID控制算法,对系统不确定部分建立灰色模型,进行灰色预测补偿。通过仿真研究,该算法具有较强的鲁棒性,可以提高控制质量,减小控制系统的误差。