共查询到19条相似文献,搜索用时 281 毫秒
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范例推理技术作为基于规则推理技术的补充,其关键就是能很好地解决知识获取的瓶颈问题,但在范例推理技术的实际应用中,如何高效建立范例库也是一个棘手的问题。采用数据挖掘技术,提出一种综合算法从传统数据库中构造范例库,可望部分解决范例获取的自动化问题,提高系统的运行效率及整体性能。 相似文献
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如何有效地建立简洁且性能可靠的范例库,以提高基于范例推理系统的性能,是当前基于范例推理研究的热点.本文结合NCL CLARA聚类算法与脚标数据的优点,给出了一种有效的基于能力的范例库自动建立新方法.通过实验表明,该方法能在保持原始领域数据库系统解决问题能力的前提下,最大程度地减少生成的范例库. 相似文献
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范例推理系统中的范例库维护 总被引:5,自引:0,他引:5
在范例推理系统中,系统的学习会使范例库逐渐增大,一般来说范例库越大,知识越丰富,但也不能无限增加,否则会大大增加相似范例检索的时间,降低系统的总体性能。因此范例推理学习系统必须有维护功能,主要目的是限制范例库的无限膨胀,且能保持系统的性能。本文在给出一个改进的删除策略维护方案的同时,并从另一角度出发,提出一个基于范例增加的维护策略,以保证系统的性能不受影响,从而达到小范例库强功能的目的。 相似文献
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能否在范例库中检索和选择出最为相似的范例决定了范例推理系统性能。文中介绍了遗传算法和模拟退火算法,比较了两种算法的特性,提出一种混合遗传模拟退火算法。该算法不但具有强的局部搜索能力,还缩短了搜索时间。将该算法用于发掘范例库上特征权重,理论分析和实验结果表明了这种混合遗传模拟退火算法优于普通的遗传算法。 相似文献
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用遗传模拟退火算法挖掘特征项权重的研究 总被引:1,自引:0,他引:1
能否在范例库中检索和选择出最为相似的范例决定了范例推理系统性能。文中介绍了遗传算法和模拟退火算法,比较了两种算法的特性.提出一种混合遗传模拟退火算法。该算法不但具有强的局部搜索能力.还缩短了搜索时间。将该算法用于发掘范例库上特征权重,理论分析和实验结果表明了这种混合遗传模拟退火算法优于普通的遗传算法。 相似文献
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Ian Watson 《Computational Intelligence》2001,17(2):387-398
This article is a case study of the maintenance required to the case base of a commercially fielded case-based reasoning (CBR) system that provides support for HVAC engineers enabling them to better specify HVAC installations. The article briefly describes the system and details how the case base grew rapidly, causing a problem of case redundancy. A simple algorithm to identify and remove redundant cases is described, along with the results of applying it to the case base. Case obsolescence also was encountered and partially remedied using DBMS techniques. The article analyzes the case-base maintenance (CBM) required by the system in terms of Richter's knowledge containers and Leake and Wilson's CBM framework and contrasts this case study with experience from NEC and DaimlerChrysler. The article observes that had maintenance of the case base been considered more explicitly during system design and implementation, some of the resulting maintenance would have been unnecessary. The article concludes by identifying lessons learned and highlighting the relationship between the sophistication of the case-representation and similarity metrics and the ease with which CBM can be undertaken by nontechnical staff. This relationship does not always work in favor of the maintainer. 相似文献
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最近的研究工作突现了在案例推理过程中案例库维护的重要性,越来越多的人认为基于案例推理系统包含了案例库维护的有关过程(Review和Restore)。案例库维护作为CBR研究的一个分支,已经研究出不同的案例库维护策略,其中一些是限制案例库的规模,由此引发了CBR系统的能力与效率问题。相似粗糙集技术可以有效地利用差别矩阵,通过不同的相似度阈值发现以及处理案例库的冗余,有选择地删除多余的案例;同时案例库的覆盖度不降低,减少了案例适应性修改的代价,从而确保了CBR系统的能力与效率的兼顾。 相似文献
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由于特征权重分配以及案例库维护对案例推理(CBR)分类器的性能有重要影响,提出了用蚁狮(ALO)算法来分配权重且用高斯混合模型的期望最大化算法(GMMEM)进行案例库维护的案例推理算法模型——AGECBR(Ant Lion and Expectation Maximization of Gaussian Mixture Model Case-Based Reasoning)。首先采用蚁狮算法对特征权重进行分配,在这个过程中将案例推理分类准确率作为蚁狮算法对特征权重进行迭代寻优的适应度函数,以此实现特征权重的优化分配;然后,使用高斯混合模型的期望最大化算法对案例库中的各案例进行聚类分析,并删除其中的噪声案例和冗余案例,从而实现案例库的维护。在UCI标准数据集上进行了实验,所提模型AGECBR比反向传播(BP)、k-近邻(kNN)等分类算法平均分类准确率提升了3.83~5.44个百分点。实验结果表明,AGECBR能够使案例推理分类准确率得到有效改进。 相似文献
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Redundancy detection in semistructured case bases 总被引:2,自引:0,他引:2
With the dramatic proliferation of case-based reasoning systems in commercial applications, many case bases are now becoming legacy systems. They represent a significant portion of an organization's assets, but they are large and difficult to maintain. One of the contributing factors is that these case bases are often large and yet unstructured or semistructured; they are represented in natural language text. Adding to the complexity is the fact that the case bases are often authored and updated by different people from a variety of knowledge sources, making it highly likely for a case base to contain redundant and inconsistent knowledge. We present methods and a system for maintaining large and semistructured case bases. We focus on a difficult problem in case base maintenance: redundancy detection. This problem is particularly pervasive when one deals with a semistructured case base. We discuss an information retrieval-based algorithm and an implemented system for solving this problem. As the ability to contain the knowledge acquisition problem is of paramount importance, our method allows one to express relevant domain expertise for detecting redundancy naturally and effortlessly. Empirical evaluations of the system demonstrate the effectiveness of the methods in several large domains 相似文献
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RFID技术作为物联网领域的关键技术,具有广阔的应用前景。然而RFID设备在读取标签信息时会产生大量冗余数据。因此,RFID数据冗余处理的研究对于减少RFID中间件系统负荷、快速检测出入标签有着重要的意义。之前针对RFID数据冗余过滤的研究往往是单维度、静态场景的简单过滤,无法实现复杂场景下标签的出入检测。因此,本文提出一种名为时间距离布隆过滤器(TDBF)的算法,该算法从时间和空间两个维度进行冗余过滤。与常用的时间布隆过滤器相比,该算法兼顾了RFID标签的读取时间和读取距离,极大的降低了数据的冗余问题。在保证漏读率较低的情况下,极大的降低了数据的误读率。同时该算法支持动态场景中移动标签的冗余过滤,能够较好的满足出入监控需求。 相似文献
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Transferring Case Knowledge To Adaptation Knowledge: An Approach for Case-Base Maintenance 总被引:5,自引:0,他引:5
Simon C. K. Shiu Daniel S. Yeung Cai H. Sun & Xi Z. Wang 《Computational Intelligence》2001,17(2):295-314
In this article we propose a case-base maintenance methodology based on the idea of transferring knowledge between knowledge containers in a case-based reasoning (CBR) system. A machine-learning technique, fuzzy decision-tree induction, is used to transform the case knowledge to adaptation knowledge. By learning the more sophisticated fuzzy adaptation knowledge, many of the redundant cases can be removed. This approach is particularly useful when the case base consists of a large number of redundant cases and the retrieval efficiency becomes a real concern of the user. The method of maintaining a case base from scratch, as proposed in this article, consists of four steps. First, an approach to learning feature weights automatically is used to evaluate the importance of different features in a given case base. Second, clustering of cases is carried out to identify different concepts in the case base using the acquired feature-weights knowledge. Third, adaptation rules are mined for each concept using fuzzy decision trees. Fourth, a selection strategy based on the concepts of case coverage and reachability is used to select representative cases. In order to demonstrate the effectiveness of this approach as well as to examine the relationship between compactness and performance of a CBR system, experimental testing is carried out using the Traveling and the Rice Taste data sets. The results show that the testing case bases can be reduced by 36 and 39 percent, respectively, if we complement the remaining cases by the adaptation rules discovered using our approach. The overall accuracies of the two smaller case bases are 94 and 90 percent, respectively, of the originals. 相似文献
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主动复制算法一般被使用在实时性要求很高的关键服务中,但这种复制算法会带来重复嵌套呼叫问题。目前,重复嵌套呼叫问题的基本解决方法在解决多极重复嵌套呼叫时存在缺陷。本文基于截获器提出一种新的过滤方法,能很好地解决多极重复嵌套呼叫问题。 相似文献