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1.
Molecular level diagnostics based on microarray technologies can offer the methodology of precise, objective, and systematic cancer classification. Genome-wide expression patterns generally consist of thousands of genes. It is desirable to extract some significant genes for accurate diagnosis of cancer because not all genes are associated with a cancer. In this paper, we have used representative gene vectors that are highly discriminatory for cancer classes and extracted multiple significant gene subsets based on those representative vectors respectively. Also, an ensemble of neural networks learned from the multiple significant gene subsets is proposed to classify a sample into one of several cancer classes. The performance of the proposed method is systematically evaluated using three different cancer types: Leukemia, colon, and B-cell lymphoma.  相似文献
2.
This paper proposes a new approach based on missing value pattern discovery for classifying incomplete data. This approach is particularly designed for classification of datasets with a small number of samples and a high percentage of missing values where available missing value treatment approaches do not usually work well. Based on the pattern of the missing values, the proposed approach finds subsets of samples for which most of the features are available and trains a classifier for each subset. Then, it combines the outputs of the classifiers. Subset selection is translated into a clustering problem, allowing derivation of a mathematical framework for it. A trade off is established between the computational complexity (number of subsets) and the accuracy of the overall classifier. To deal with this trade off, a numerical criterion is proposed for the prediction of the overall performance. The proposed method is applied to seven datasets from the popular University of California, Irvine data mining archive and an epilepsy dataset from Henry Ford Hospital, Detroit, Michigan (total of eight datasets). Experimental results show that classification accuracy of the proposed method is superior to those of the widely used multiple imputations method and four other methods. They also show that the level of superiority depends on the pattern and percentage of missing values.  相似文献
3.
针对肿瘤基因表达谱样本少,维数高的特点,提出一种用于肿瘤信息基因提取和亚型识别的集成分类器算法.该算法根据基因的Fisher比率值建立候选子集,再采用相关系数和互信息两种度量方法,分别构造反映基因共表达行为和调控关系的特征子集.粒子群优化算法分别与SVM和KNN构成两个基分类器,从候选子集中提取信息基因并对肿瘤亚型进行分类,最后利用绝对多数投票方法对基分类器的结果进行整合.G.Gordon肺癌亚型识别的实验结果表明了该算法的可行性和有效性.  相似文献
4.
Due to the wide variety of fusion techniques available for combining multiple classifiers into a more accurate classifier, a number of good studies have been devoted to determining in what situations some fusion methods should be preferred over other ones. However, the sample size behavior of the various fusion methods has hitherto received little attention in the literature of multiple classifier systems. The main contribution of this paper is thus to investigate the effect of training sample size on their relative performance and to gain more insight into the conditions for the superiority of some combination rules.A large experiment is conducted to study the performance of some fixed and trainable combination rules for executing one- and two-level classifier fusion for different training sample sizes. The experimental results yield the following conclusions: when implementing one-level fusion to combine homogeneous or heterogeneous base classifiers, fixed rules outperform trainable ones in nearly all cases, with only one exception of merging heterogeneous classifiers for large sample size. Moreover, the best classification for any considered sample size is generally achieved by a second level of combination (namely, utilizing one fusion rule to further combine a set of ensemble classifiers with each of them constructed by fusing base classifiers). Under these circumstances, it seems that adopting different types of fusion rules (fixed or trainable) as the combiners for two levels of fusion is appropriate.  相似文献
5.
针对不平衡噪声数据流的分类问题,本文利用基于平均概率的集成分类器AP与抽样技术,提出了一种处理不平衡噪声数据流的集成分类器(IMDAP)模型。实验结果表明,该集成分类器更能适应存在概念漂移与噪声的不平衡数据流挖掘分类,其整体分类性能优于AP集成分类器模型,能明显提升少数类的分类精度,并且具有与AP相近的时间复杂度。  相似文献
6.
词义消歧一直是自然语言处理中的热点和难题.集成方法被认为是机器学习研究的四大趋势之一,在系统研究已有集成学习方法在汉语词义消歧中的应用后,借鉴模式识别领域集成分类器思想,提出了一种动态自适应加权投票的多分类器集成方法来构建融合分类器.实验结果表明,所提融合分类器模型对汉语文本自动消歧结果的准确率提高较大.  相似文献
7.
已有的数据流分类算法多采用有监督学习,需要使用大量已标记数据训练分类器,而获取已标记数据的成本很高,算法缺乏实用性.针对此问题,文中提出基于半监督学习的集成分类算法SEClass,能利用少量已标记数据和大量未标记数据,训练和更新集成分类器,并使用多数投票方式对测试数据进行分类.实验结果表明,使用同样数量的已标记训练数据,SEClass算法与最新的有监督集成分类算法相比,其准确率平均高5.33%.且运算时间随属性维度和类标签数量的增加呈线性增长,能够适用于高维、高速数据流分类问题.  相似文献
8.
The article presents a new approach of calculating the weight of base classifiers from a committee of classifiers. The obtained weights are interpreted in the context of the interval-valued sets. The work proposes four different ways of calculating weights which consider both the correctness and incorrectness of the classification. The proposed weights have been used in the algorithms which combine the outputs of base classifiers. In this work we use both the outputs, represented by rank and measure level. Research experiments have involved several bases available in the UCI repository and two data sets that have generated distributions. The performed experiments compare algorithms which are based on calculating the weights according to the resubstitution and algorithms proposed in the work. The ensemble of classifiers has also been compared with the base classifiers entering the committee.  相似文献
9.
为了进一步提高批量隐写的安全性, 针对以往自适应批量隐写方案的不足设计了一种简单可靠的新方案。首先借助基于随机森林的集成分类器确定当前隐写分析技术下图像的隐写容量, 在此基础上确定各个图像嵌入的信息量, 方案最大程度地利用了载体资源, 并通过对秘密信息进行分割分组进一步增强了安全性。实验结果表明, 隐写容量计算中的安全判定方法准确性高, 在保证低漏检率的同时避免了较高的虚警率, 且运行时间更短。  相似文献
10.
N-gram字符序列能有效捕捉文本中作者的个体风格信息,但其特征空间稀疏度高,且存在较多噪音特征。针对该问题,提出一种基于半随机特征采样的中文书写纹识别算法。该算法首先采用一种离散度准则为每个作者选取一定粒度的个体特征集,然后将个体特征集以一种半随机选择机制划分成多个等维度的特征子空间,并基于每个子空间训练相应的基分类器,最后采取多数投票法的融合策略构造集成分类模型。在中文真实数据集上与基于随机子空间和Bagging算法的集成分类器进行了对比试验,结果表明,该算法在正确率和差异度方面优于随机子空间和Baggrog算法,并且取得了比单分类模型更好的识别性能。  相似文献
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