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基于大数据随机样本划分的分布式观测点分类器
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作者 李旭 何玉林 +2 位作者 崔来中 黄哲学 philippe fournier-viger 《计算机应用》 CSCD 北大核心 2024年第6期1727-1733,共7页
观测点分类器(OPC)是一种试图通过将多维样本空间线性不可分问题转换成一维距离空间线性可分问题的有监督学习模型,对高维数据的分类问题尤为有效。针对OPC在处理大数据分类问题时表现的较高训练复杂度,在Spark框架下设计一款基于大数... 观测点分类器(OPC)是一种试图通过将多维样本空间线性不可分问题转换成一维距离空间线性可分问题的有监督学习模型,对高维数据的分类问题尤为有效。针对OPC在处理大数据分类问题时表现的较高训练复杂度,在Spark框架下设计一款基于大数据的随机样本划分(RSP)的分布式OPC(DOPC)。首先,在分布式计算环境下生成大数据的RSP数据块,并将它转换为弹性分布式数据集(RDD);其次,在RSP数据块上协同式地训练一组OPC,由于每个RSP数据块上的OPC独立训练,因此有高效的Spark可实现性;最后,在Spark框架下将在RSP数据块上协同训练的OPC集成为DOPC,对新样本进行类标签预测。在8个大数据集上,对Spark集群环境下实现的DOPC的可行性、合理性和有效性进行实验验证,实验结果显示,DOPC能够以更低的计算消耗获得比单机OPC更高的测试精度,同时相较于Spark框架下实现的基于RSP模型的神经网络(NN)、决策树(DT)、朴素贝叶斯(NB)和K最近邻(KNN),DOPC分类器具有更强的泛化性能。测试结果表明,DOPC是一种高效低耗的处理大数据分类问题的有监督学习算法。 展开更多
关键词 大数据分类 分布式文件系统 随机样本划分 观测点分类器 Spark计算框架
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基于分类风险的半监督集成学习算法
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作者 何玉林 朱鹏辉 +1 位作者 黄哲学 philippe fournier-viger 《模式识别与人工智能》 EI CSCD 北大核心 2024年第4期339-351,共13页
针对当前半监督集成学习算法对无标记样本预测时容易出现的标注混沌问题,文中提出基于分类风险的半监督集成学习算法(Classification Risk-Based Semi-supervised Ensemble Learning Algorithm,CR-SSEL).采用分类风险作为无标记样本置... 针对当前半监督集成学习算法对无标记样本预测时容易出现的标注混沌问题,文中提出基于分类风险的半监督集成学习算法(Classification Risk-Based Semi-supervised Ensemble Learning Algorithm,CR-SSEL).采用分类风险作为无标记样本置信度的评判标准,可有效衡量样本标注的不确定性程度.迭代地训练分类器,对高置信度样本进行再强化,使样本标注的不确定性逐渐降低,增强半监督集成学习算法的分类性能.在多个标准数据集上验证CR-SSEL的学习参数影响、训练过程收敛和泛化性能提升,实验表明随着基分类器个数的增加,CR-SSEL的训练过程呈收敛趋势,获得较优的分类精度. 展开更多
关键词 半监督集成学习 集成学习 半监督学习 分类风险 不确定性 置信度
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Multi-scale persistent spatiotemporal transformer for long-term urban traffic flow prediction
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作者 Jia-Jun Zhong Yong Ma +3 位作者 Xin-Zheng Niu philippe fournier-viger Bing Wang Zu-kuan Wei 《Journal of Electronic Science and Technology》 EI CAS CSCD 2024年第1期53-69,共17页
Long-term urban traffic flow prediction is an important task in the field of intelligent transportation,as it can help optimize traffic management and improve travel efficiency.To improve prediction accuracy,a crucial... Long-term urban traffic flow prediction is an important task in the field of intelligent transportation,as it can help optimize traffic management and improve travel efficiency.To improve prediction accuracy,a crucial issue is how to model spatiotemporal dependency in urban traffic data.In recent years,many studies have adopted spatiotemporal neural networks to extract key information from traffic data.However,most models ignore the semantic spatial similarity between long-distance areas when mining spatial dependency.They also ignore the impact of predicted time steps on the next unpredicted time step for making long-term predictions.Moreover,these models lack a comprehensive data embedding process to represent complex spatiotemporal dependency.This paper proposes a multi-scale persistent spatiotemporal transformer(MSPSTT)model to perform accurate long-term traffic flow prediction in cities.MSPSTT adopts an encoder-decoder structure and incorporates temporal,periodic,and spatial features to fully embed urban traffic data to address these issues.The model consists of a spatiotemporal encoder and a spatiotemporal decoder,which rely on temporal,geospatial,and semantic space multi-head attention modules to dynamically extract temporal,geospatial,and semantic characteristics.The spatiotemporal decoder combines the context information provided by the encoder,integrates the predicted time step information,and is iteratively updated to learn the correlation between different time steps in the broader time range to improve the model’s accuracy for long-term prediction.Experiments on four public transportation datasets demonstrate that MSPSTT outperforms the existing models by up to 9.5%on three common metrics. 展开更多
关键词 Graph neural network Multi-head attention mechanism Spatio-temporal dependency Traffic flow prediction
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自训练新类探测半监督学习算法
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作者 何玉林 陈佳琪 +2 位作者 黄启航 菲律普弗尼尔-维格 黄哲学 《计算机科学与探索》 CSCD 北大核心 2023年第9期2184-2197,共14页
传统的半监督学习算法(SSL)存在适用范围有限和泛化能力不足的缺陷,尤其是当训练数据集中出现未见标签的新类样本时,算法的性能将在很大程度上受到影响。基于人工标注的有标记样本获取方式需要领域专家的参与,消耗了高昂的时间和财力成... 传统的半监督学习算法(SSL)存在适用范围有限和泛化能力不足的缺陷,尤其是当训练数据集中出现未见标签的新类样本时,算法的性能将在很大程度上受到影响。基于人工标注的有标记样本获取方式需要领域专家的参与,消耗了高昂的时间和财力成本,且由于专家背景知识的局限,无法避免标记过程中的人为错标现象。为此,以提高对未见标签样本标注正确性为出发点的半监督学习算法具有迫切的实际需要。在对自训练算法进行了详细剖析之后,提出了一种有效的新类探测半监督学习算法(NCD-SSL)。首先,基于经典的极限学习机模型,构造了可处理标签增量和样本增量学习的通用增量极限学习机;然后,对自训练算法进行改进,利用标注可信度高的样本进行样本增量学习,同时设置了缓存池用以存储标注可信度低的样本;之后,使用聚类和分布一致性判定方法进行新类探测,进而实现类增量学习;最后,在仿真数据集和真实数据集上对提出算法的可行性和有效性进行了实验验证,实验结果显示在缺失类别数为3、2、1时,新算法的测试精度普遍比其他6种半监督学习算法高出30、20、10个百分点左右,从而证实了提出的算法能够获得更好的新类探测半监督学习表现。 展开更多
关键词 半监督学习(SSL) 新类探测 自训练 极限学习机 最大平均差异 分布一致性
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Identifying Causes Helps a Tutoring System to Better Adapt to Learners during Training Sessions
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作者 Usef Faghihi philippe fournier-viger +1 位作者 Roger Nkambou Pierre Poirier 《Journal of Intelligent Learning Systems and Applications》 2011年第3期139-154,共16页
This paper describes a computational model for the implementation of causal learning in cognitive agents. The Conscious Emotional Learning Tutoring System (CELTS) is able to provide dynamic fine-tuned assistance to us... This paper describes a computational model for the implementation of causal learning in cognitive agents. The Conscious Emotional Learning Tutoring System (CELTS) is able to provide dynamic fine-tuned assistance to users. The integration of a Causal Learning mechanism within CELTS allows CELTS to first establish, through a mix of datamining algorithms, gross user group models. CELTS then uses these models to find the cause of users' mistakes, evaluate their performance, predict their future behavior, and, through a pedagogical knowledge mechanism, decide which tutoring intervention fits best. 展开更多
关键词 Cognitive Agents Computational CAUSAL Modeling and Learning Emotions
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CLS-Miner: efficient and effective closed high-utility itemset mining 被引量:10
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作者 Thu-Lan DAM Kenli LI +1 位作者 philippe fournier-viger Quang-Huy DUONG 《Frontiers of Computer Science》 SCIE EI CSCD 2019年第2期357-381,共25页
High-utility itemset mining (HUIM) is a popular data mining task with applications in numerous domains. However, traditional HUIM algorithms often produce a very large set of high-utility itemsets (HUIs). As a result,... High-utility itemset mining (HUIM) is a popular data mining task with applications in numerous domains. However, traditional HUIM algorithms often produce a very large set of high-utility itemsets (HUIs). As a result, analyzing HUIs can be very time consuming for users. Moreover, a large set of HUIs also makes HUIM algorithms less efficient in terms of execution time and memory consumption. To address this problem, closed high-utility itemsets (CHUIs), concise and lossless representations of all HUIs, were proposed recently. Although mining CHUIs is useful and desirable, it remains a computationally expensive task. This is because current algorithms often generate a huge number of candidate itemsets and are unable to prune the search space effectively. In this paper, we address these issues by proposing a novel algorithm called CLS-Miner. The proposed algorithm utilizes the utility-list structure to directly compute the utilities of itemsets without producing candidates. It also introduces three novel strategies to reduce the search space, namely chain-estimated utility co-occurrence pruning, lower branch pruning, and pruning by coverage. Moreover, an effective method for checking whether an itemset is a subset of another itemset is introduced to further reduce the time required for discovering CHUIs. To evaluate the performance of the proposed algorithm and its novel strategies, extensive experiments have been conducted on six benchmark datasets having various characteristics. Results show that the proposed strategies are highly efficient and effective, that the proposed CLS-Miner algorithm outperforms the current state-ofthe- art CHUD and CHUI-Miner algorithms, and that CLSMiner scales linearly. 展开更多
关键词 UTILITY MINING high-utility ITEMSET MINING CLOSED ITEMSET MINING CLOSED high-utility ITEMSET MINING
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