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在许多实际的应用场景中,数据测量的误差、对数据的理解和传输失真等都会导致数据的丢失,这种数据不完整的形式背景即为不完备形式背景。为了丰富不完备形式背景中的知识获取模型,文中结合三支思想在不完备形式背景中利用正算子与粗糙集理论中的必然-可能性算子构造了共同-可能(cp)近似概念,讨论了对象诱导的共同-可能(cp)近似概念与经典概念、面向属性概念、对象诱导的三支近似概念的关系,提出了由经典概念和面向属性概念构造对象诱导的cp-近似概念的算法。进而,基于OE-cp-近似概念讨论了不完备决策形式背景中近似决策规则的获取,提出了OE-cp-协调的不完备决策形式背景下的正规则和可能性规则,并给出了与基于经典概念的决策规则之间的关系。 相似文献
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基于模拟退火算法的知识获取方法的研究 总被引:7,自引:1,他引:7
从优化角度提出了从事例中获取知识的机器学习方法。该方法利用模拟退火算法,按照预定的优化目标,从事例中生成最优的产生式规则,给出其算法,并以旋转机械故障诊断知识获取为例,阐述了基于模拟退火算法的知识获取机制及其实现方法。 相似文献
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智能故障诊断系统中的知识发现方法 总被引:2,自引:0,他引:2
从数理统计和关联规则的综合性出发,提出了一种从事例集中获取知识的机器学习方法。该方法利用Matlab进行编程,按照预定的优化目标生成最优的产生式规则。以旋转机械故障诊断知识发现为例进行了仿真实现,从中可获取各类故障的最优判别功能。结果表明,该方法是可行的,它验证了该方法在旋转机械故障诊断中的实用性和有效性。 相似文献
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针对密闭鼓风炉故障诊断中难以获得大量故障数据样本以及特征提取和诊断知识获取困难等不足,提出了应用支持向量机(SVM)进行故障诊断的新方法.采用改进"1对其余"算法构建多个SVM,利用可靠性数据分析技术中一些基本概念处理原始样本数据作为特征向量,输入到由多个SVM构成的多类分类器中进行故障分类.经实验证明,该方法简单,重复训练量少,训练、分类速度快,准确度高. 相似文献
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青河 《电子制作.电脑维护与应用》2013,(7):229
本文以计算机硬件售后的维修服务为模型,为计算机硬件出现的故障及对应解决方案创建知识库.硬件故障知识采用事例表示法和产生式规则表示法两种方法,并将知识分为事例知识和规则知识两类.在事例知识的获取方面采用了自动获取和人工干预两种形式,在规则知识的获取方面采用的是人工干预形式. 相似文献
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针对导弹故障诊断过程中出现信息缺失、数据不完备的问题,提出一种基于流向图的导弹故障诊断知识的获取方法;首先,提取故障特征信息,并利用特征关系对故障诊断知识进行分类处理,得到同一特征关系下的故障诊断实例集合;然后,建立不完备故障诊断流向图,并表述出各个节点之间的置信度和覆盖度,作为衡量完整路径的指标,构建导弹故障诊断知识获取框架;最后,结合实例分析,验证该故障诊断知识获取方法具有较好的直观性,为导弹故障诊断工作提供有效参考。 相似文献
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为解决复杂装备故障诊断中的知识获取和决策制定问题,提出一种数据驱动的故障诊断方法。利用模糊贝叶斯风险模型以风险最小化原则挖掘数据中有价值知识,得到相对最优属性子集,其中生成的概率分布用于T-S(Takagi-Sugeno)模糊规则提取,以分段线性化思想逼近复杂的数据知识。在数值实验中,以C-MAPSS(Commercial Modular Aero-Propulsion System Simulation)发动机数据为研究对象,验证本文方法的有效性,结果表明本文方法适用于复杂装备的故障诊断。与其他知识获取方法对比表明,本文方法可得到更高的诊断准确率。 相似文献
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针对密闭鼓风炉故障信息的复杂性和不完备性,建立了基于粗糙集(RS)和最小二乘支持向量机(LS_SVM)相结合的故障诊断模型。首先运用等频率划分法对故障诊断数据中的连续属性进行离散化,然后采用粗糙集理论进行故障诊断决策系统约简,获得最优决策系统。将约简结果与LS_SVM相结合,建立了故障诊断模型。实验结果表明,该模型提高了诊断效率和判断准确率。 相似文献
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粗糙集理论具有很强的定性分析能力,能够有效地表达不确定的或不精确的知识,善于从数据中获取知识,并能利用不确定、不完整的经验知识进行推理。利用粗糙集理论,以房地产信息为实例,通过粗糙集的属性约简和规则提取方法,得到更多房地产信息中潜在的规律,为购房者提供更多的参考。 相似文献
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一种基于模糊粗糙集知识获取方法 总被引:1,自引:1,他引:1
本文介绍了粗糙集和模糊粗糙集的上下近似。并且利用模糊粗糙上下近似算子,论述了在不完备模糊信息系统中知识获取的一种方法。应用这种方法能够让隐藏在不完备模糊信息系统中的知识,以决策规则的形式表示出来。最后给出了一种实现算法和实例。 相似文献
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Learning rules from incomplete training examples by rough sets 总被引:1,自引:0,他引:1
Machine learning can extract desired knowledge from existing training examples and ease the development bottleneck in building expert systems. Most learning approaches derive rules from complete data sets. If some attribute values are unknown in a data set, it is called incomplete. Learning from incomplete data sets is usually more difficult than learning from complete data sets. In the past, the rough-set theory was widely used in dealing with data classification problems. In this paper, we deal with the problem of producing a set of certain and possible rules from incomplete data sets based on rough sets. A new learning algorithm is proposed, which can simultaneously derive rules from incomplete data sets and estimate the missing values in the learning process. Unknown values are first assumed to be any possible values and are gradually refined according to the incomplete lower and upper approximations derived from the given training examples. The examples and the approximations then interact on each other to derive certain and possible rules and to estimate appropriate unknown values. The rules derived can then serve as knowledge concerning the incomplete data set. 相似文献
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Knowledge acquisition in incomplete fuzzy information systems via the rough set approach 总被引:15,自引:0,他引:15
Abstract: Machine learning can extract desired knowledge from training examples and ease the development bottleneck in building expert systems. Most learning approaches derive rules from complete and incomplete data sets. If attribute values are known as possibility distributions on the domain of the attributes, the system is called an incomplete fuzzy information system. Learning from incomplete fuzzy data sets is usually more difficult than learning from complete data sets and incomplete data sets. In this paper, we deal with the problem of producing a set of certain and possible rules from incomplete fuzzy data sets based on rough sets. The notions of lower and upper generalized fuzzy rough approximations are introduced. By using the fuzzy rough upper approximation operator, we transform each fuzzy subset of the domain of every attribute in an incomplete fuzzy information system into a fuzzy subset of the universe, from which fuzzy similarity neighbourhoods of objects in the system are derived. The fuzzy lower and upper approximations for any subset of the universe are then calculated and the knowledge hidden in the information system is unravelled and expressed in the form of decision rules. 相似文献
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Theory and applications of granular labelled partitions in multi-scale decision tables 总被引:1,自引:0,他引:1
Wei-Zhi Wu 《Information Sciences》2011,181(18):3878-3897
Granular computing and acquisition of if-then rules are two basic issues in knowledge representation and data mining. A formal approach to granular computing with multi-scale data measured at different levels of granulations is proposed in this paper. The concept of labelled blocks determined by a surjective function is first introduced. Lower and upper label-block approximations of sets are then defined. Multi-scale granular labelled partitions and multi-scale decision granular labelled partitions as well as their derived rough set approximations are further formulated to analyze hierarchically structured data. Finally, the concept of multi-scale information tables in the context of rough set is proposed and the unravelling of decision rules at different scales in multi-scale decision tables is discussed. 相似文献
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Patrick G. Clark Jerzy W. Grzymala-Busse Wojciech Rzasa 《Journal of Intelligent Information Systems》2016,47(3):515-529
A probabilistic approximation is a generalization of the standard idea of lower and upper approximations, defined for equivalence relations. Recently probabilistic approximations were additionally generalized to an arbitrary binary relation so that probabilistic approximations may be applied for incomplete data. We discuss two ways to induce rules from incomplete data using probabilistic approximations, by applying true MLEM2 algorithm and an emulated MLEM2 algorithm. In this paper we report novel research on a comparison of both approaches: new results of experiments on incomplete data with three interpretations of missing attribute values. Our results show that both approaches do not differ much. 相似文献
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提出了一种基于Rough集理论的Self集构造和演化算法。利用Rough集约简算法,对用户的安全访问行为的数据作规范化处理并进行约简,从中提取有效的最简规则,降低了安全数据的冗余,减轻了特征码构造的负担。使用Rough集上、下近似集原理,构造了上、下近似Self集,实现了Self的优化和扩展,有效地解决了Self集的自动演化问题。 相似文献