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从不确定图中挖掘频繁子图模式 被引量:32
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作者 邹兆年 李建中 +1 位作者 高宏 张硕 《软件学报》 EI CSCD 北大核心 2009年第11期2965-2976,共12页
研究不确定图数据的挖掘,主要解决不确定图数据的频繁子图模式挖掘问题.介绍了一种数据模型来表示图的不确定性,以及一种期望支持度来评价子图模式的重要性.利用期望支持度的Apriori性质,给出了一种基于深度优先搜索策略的挖掘算法.该... 研究不确定图数据的挖掘,主要解决不确定图数据的频繁子图模式挖掘问题.介绍了一种数据模型来表示图的不确定性,以及一种期望支持度来评价子图模式的重要性.利用期望支持度的Apriori性质,给出了一种基于深度优先搜索策略的挖掘算法.该算法使用高效的期望支持度计算方法和搜索空间裁剪技术,使得计算子图模式的期望支持度所需的子图同构测试的数量从指数级降低到线性级.实验结果表明,该算法比简单的深度优先搜索算法快3-5个数量级,有很高的效率和可扩展性. 展开更多
关键词 不确定 挖掘 频繁子图模式
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联合子图模式和网络表征的路网链路预测模型 被引量:1
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作者 王斌 李毅磊 +2 位作者 盛津芳 孙泽军 卢奔 《小型微型计算机系统》 CSCD 北大核心 2019年第11期2357-2364,共8页
城市道路网络(简称路网)是一种结构复杂且高度稀疏的网络,对城市道路网络进行链路预测能够对城市结构变化进行合理预演,辅助城市设计者决策.本文针对路网特性提出了一种新的链路预测模型GRSC,该模型首先通过road2vec对路网进行网络表征... 城市道路网络(简称路网)是一种结构复杂且高度稀疏的网络,对城市道路网络进行链路预测能够对城市结构变化进行合理预演,辅助城市设计者决策.本文针对路网特性提出了一种新的链路预测模型GRSC,该模型首先通过road2vec对路网进行网络表征,然后将子图模式和网络表征结果有机地结合起来,共同构建包含子图结构特征、游走距离特征的广义路网子图特征,最后训练logistic回归分类模型,用于路网链路预测.实验对比了GRSC模型和其它链路预测模型在不同国家、不同类型城市路网上的表现以及模型参数的变化对预测精度的影响,结果表明,GRSC在预测精度和稳定性方面都表现良好. 展开更多
关键词 链路预测 子图模式 网络表征 分类模型 城市路网
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基于子图模式的网络流量分类方法研究 被引量:3
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作者 杨季 石亮山 +2 位作者 陈波 汪明达 胡光岷 《计算机应用研究》 CSCD 北大核心 2014年第6期1816-1819,共4页
盲分类(blind classification,BLINC)方法提出利用不同网络应用在传输层子图连接模式的差异对网络流量进行分类,获得了良好的效果,该方法分类的准确度较高,但是完整度则相对较低。为了解决BLINC分类完整度较低的问题,借鉴BLINC的分类思... 盲分类(blind classification,BLINC)方法提出利用不同网络应用在传输层子图连接模式的差异对网络流量进行分类,获得了良好的效果,该方法分类的准确度较高,但是完整度则相对较低。为了解决BLINC分类完整度较低的问题,借鉴BLINC的分类思想,提出了基于子图模式的流分类方法,该方法综合运用源节点子图模式、目的节点子图模式和端口分析技术。实验证明,在同样阈值的条件下该方法对同样一组Web、DNS、Mail、FTP、P2P流量数据进行分类,准确度与传统BLINC方法基本保持一致,但是完整度得到了明显的提高,具有很好的实用性。 展开更多
关键词 流量分类 盲分类 匹配 子图模式
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基于子图模式的反恐情报关联图集分析 被引量:3
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作者 李勇男 《现代情报》 CSSCI 2019年第7期37-43,共7页
[目的/意义]利用子图模式对暴恐案件中的人员关联进行分析可以发现涉恐人员关联图中的规律,为反恐情报分析提供有效参考。[方法/过程]首先对涉恐基础数据进行预处理,保证图中各顶点的唯一性。通过计数统计出所有的频繁1-子图和频繁2-子... [目的/意义]利用子图模式对暴恐案件中的人员关联进行分析可以发现涉恐人员关联图中的规律,为反恐情报分析提供有效参考。[方法/过程]首先对涉恐基础数据进行预处理,保证图中各顶点的唯一性。通过计数统计出所有的频繁1-子图和频繁2-子图,然后不断迭代生成其他候选子图并筛选频繁子图,直到达到终止条件为止。[结果/结论]该方法根据反恐情报的特点进行了优化,避免了普通频繁子图挖掘中的大量图同构检测,挖掘出的频繁子图可以反映不同类别涉恐人员之间的联系规律和联系特点,发现暴恐案件线索,有效预测和打击恐怖活动。 展开更多
关键词 子图模式 反恐情报 数据挖掘 候选 同构
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一种有效的在不确定图数据库中挖掘频繁子图模式的MUSIC算法
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作者 王文龙 李建中 《智能计算机与应用》 2013年第5期20-23,共4页
近年来,如何在不确定图数据库中挖掘频繁子图模式得到了越来越多的关注。该问题的主要难点在于,不仅存在着海量的可能子图模式需要检验,而且还需要做大数量的子图同构性测试来判别图中是否蕴含一个给定的模式。传统的算法是利用近似算... 近年来,如何在不确定图数据库中挖掘频繁子图模式得到了越来越多的关注。该问题的主要难点在于,不仅存在着海量的可能子图模式需要检验,而且还需要做大数量的子图同构性测试来判别图中是否蕴含一个给定的模式。传统的算法是利用近似算法计算子图模式的期望支持度,但计算开销仍然十分巨大。为此提供一个基于建立在不确定数据库上的索引的算法。算法首先根据apriori性质枚举所有可能的首选子图模式,然后利用索引对候选子图模式空间进行剪枝以减少子图同构性检验从而减少期望支持度的计算开销。通过在一个真实数据集上的实验显示本算法可以有效地在不确定图数据库中挖掘频繁子图模式。 展开更多
关键词 不确定 频繁子图模式 期望支持度 不确定索引
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基于出行模式子图的城市功能区域发现方法 被引量:5
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作者 肖飞 王悦 +2 位作者 梅逸男 白璐 崔丽欣 《计算机科学》 CSCD 北大核心 2018年第12期268-278,共11页
城市的功能区域是指在城市的发展过程中逐渐形成的功能(如工业、商业、居住、教育等)相对固定的地理区域。这些区域间的位置结构影响着城市中居民的出行模式,与此同时,城市居民的出行模式也客观地反映了城市不同区域的真实的功能定位。... 城市的功能区域是指在城市的发展过程中逐渐形成的功能(如工业、商业、居住、教育等)相对固定的地理区域。这些区域间的位置结构影响着城市中居民的出行模式,与此同时,城市居民的出行模式也客观地反映了城市不同区域的真实的功能定位。文中以出租车运行轨迹数据为基础,研究城市居民的出行模式,并根据所得模式实现城市功能区域的自动化发现。主要思路及贡献包括:1)使用车辆轨迹及路网结构数据构造区域模式图(region pattern graph)结构,并提出区域模式图构建算法,采用图结构将城市的不同地理区域连接起来;2)提出自底而上的功能区域发现算法(Bottom-Up Functional Region Discovering,BUFRD)框架及基本实现思路,包括提出频繁出行模式子图挖掘算法,发现区域模式图中频繁出现的出行模式;3)提出功能区域聚类算法,聚类已获取的出行模式子图集,并最终实现城市功能区域的发现。实验结果表明,通过所提方法发现的城市功能区域较传统方法所得结果的功能纯度更高,其熵值比传统方法降低了至少10%。 展开更多
关键词 城市大数据 数据挖掘 城市功能区域 出行模式
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多样性度量的Top-K区分子图挖掘 被引量:1
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作者 王章辉 赵宇海 +1 位作者 王国仁 李源 《计算机科学与探索》 CSCD 北大核心 2017年第9期1379-1388,共10页
区分子图可以用来描述复杂的图数据结构和构建高效的图分类模型。提出了多样性度量的Top-K区分子图挖掘问题,避免了挖掘结果之间出现高度相关的子图模式,提高了区分子图模式的可用性。通过组合图结构相似性与支持集相似性约束,给出图模... 区分子图可以用来描述复杂的图数据结构和构建高效的图分类模型。提出了多样性度量的Top-K区分子图挖掘问题,避免了挖掘结果之间出现高度相关的子图模式,提高了区分子图模式的可用性。通过组合图结构相似性与支持集相似性约束,给出图模式的多样性度量标准。提出两个高效算法Greedy-TopK和LeapTopK挖掘多样性度量的Top-K区分子图。Greedy-TopK算法采用两阶段的增量式贪婪方法快速挖掘K个区分子图模式。Leap-TopK算法通过在挖掘过程中限制扩展结构相似的图模式,实现了跳跃搜索子图模式空间。实验结果表明,Leap-TopK算法的效率明显优于Greedy-TopK算法;在可用性方面,利用Leap-TopK算法与Greedy-TopK算法挖掘结果构建的图分类器具有相似的分类精度,且都优于传统区分子图挖掘算法产生的结果。 展开更多
关键词 挖掘 分类 子图模式 区分 多样性
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二分类图上的非冗余协同图模式挖掘算法
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作者 王章辉 赵宇海 +1 位作者 王国仁 李源 《计算机学报》 EI CSCD 北大核心 2015年第7期1434-1447,共14页
图模式广泛应用于构建高效图分类模型的特征空间识别.协同图模式是一种内部节点高度相关的图结构,与普通图模式相比,协同图模式具有更高的区分能力,从而更加适用于分类模型的特征选择.文中研究了从二分类图中挖掘非冗余协同图模式的问题... 图模式广泛应用于构建高效图分类模型的特征空间识别.协同图模式是一种内部节点高度相关的图结构,与普通图模式相比,协同图模式具有更高的区分能力,从而更加适用于分类模型的特征选择.文中研究了从二分类图中挖掘非冗余协同图模式的问题,通过限制协同图模式的区分能力远远高于其所有子图模式的非冗余性质,大幅度减少了挖掘结果的数量,同时保留了具有强区分能力的协同图模式.由于协同图模式理论上必须检测其所有子图是否满足约束条件,挖掘它们非常具有计算挑战性.基于非冗余协同图模式的多种特性,提出相对应的削减规则;通过对区分能力的边界估计,提出两个快速检测非冗余协同图模式方法,在此基础上给出了一种高效的深度优先挖掘算法GINS.大量真实与合成数据集上的实验结果表明,GINS算法明显优于其他两个代表性算法,作为图分类模型的分类特征时,非冗余协同图模式获得了较高的分类精度. 展开更多
关键词 二分类 非冗余 协同模式 分类 挖掘 子图模式 分类器
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Experimental Study on the Flow Around Two Tandem Cylinders with Unequal Diameters 被引量:4
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作者 GAO Yangyang ETIENNE Stephane +1 位作者 WANG Xikun TAN Soon Keat 《Journal of Ocean University of China》 SCIE CAS 2014年第5期761-770,共10页
In this paper, flow around two circular cylinders in tandem arrangement with unequal diameters has been investigated using the particle image velocimetry technique(PIV) in a water channel. The upstream to downstream d... In this paper, flow around two circular cylinders in tandem arrangement with unequal diameters has been investigated using the particle image velocimetry technique(PIV) in a water channel. The upstream to downstream diameter ratio was kept constant at d/D = 2/3, the centre-to-centre distance was varied from 1.2D to 5D and the Reynolds number was varied from 1200 to 4800. The flow characteristics were analyzed through ensemble-averaged patterns of velocity, vorticity, normalized Reynolds stress contours and streamlines. Based on ensemble-averaged and instantaneous flow fields, different flow patterns, including single-wakeshedding at small spacing ratio, bi-stable flow behavior(alternating behavior of reattachment and vortex shedding) at intermediate spacing ratio and co-shedding pattern at large spacing ratio were observed. The effects of Reynolds number and the centre-to-centre spacing ratio on flow patterns and turbulent characteristics were also investigated. It was found that the diameter ratio appears to have a certain effect on the flow patterns at intermediate spacing ratios, where the reattachment of shear layer depends on the lateral width of the wake flow in the lee of the upstream cylinder. Extensive discussion on the distributions of Reynolds stress and turbulent kinetic energy was presented. 展开更多
关键词 tandem cylinders with unequal diameters PIV flow patterns Reynolds stress distribution
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Superlattice Patterns in Coupled Turing Systems 被引量:1
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作者 刘富成 贺亚峰 潘宇扬 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第5期971-976,共6页
In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Th... In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns. 展开更多
关键词 superlattice pattern turing instability mode interaction
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Transported into the Bosom of the Empire? Rethinking How Arthur Conan Doyle Persuades His Readers of British Imperialism in "The Speckled Band"
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作者 黄斌峰 《Journalism and Mass Communication》 2015年第4期194-205,共12页
Melanie C. Green and Timothy C. Brock have proposed their transportation-imagery model of narrative persuasion. They argue that a narrative can evoke imagery in readers' mind and then transport readers into the narra... Melanie C. Green and Timothy C. Brock have proposed their transportation-imagery model of narrative persuasion. They argue that a narrative can evoke imagery in readers' mind and then transport readers into the narrative world the author has created, in the course of which the author can persuade readers of the beliefs he's put into the narrative. This paper employs this model to rethink how Arthur Conan Doyle persuades his readers of British imperialism in his "The Speckled Band". First, this model considers the vividness of the narrative and readers' participatory response as key factors in readers' transportation. The narratives of "The Speckled Band" are picturesque, and Sherlock Holmes' inferential process has reinforced readers' participatory response. On the other hand, detective fiction usually has the theme of how the detective/law and order beats the criminal/chaos. That is, Doyle persuades his readers that the British Empire will prevail in "The Speckled Band" when Holmes, representing the British imperialism, solves the case and kills Dr. Roylott, who represents the evil and savagery in the British colony. According to Green and Brock's model, it simply means that there are two narratives (i.e., one is about how the law of the British Empire is challenged, and the other is about how the British Empire's stability is restored), and two complementary transportations before Doyle can successfully persuades his readers. However, if we closely read "'The Speckled Band", we can learn that Holmes, who should have represented British law, is guilty of trespassing or taking the law into his own hands. In other words, the complementarity of the two transportations is compromised. Thus, we can conclude that it is highly questionable whether or not Doyle can transport his readers into the bosom of the British Empire. 展开更多
关键词 Arthur Conan Doyle "The Speckled Band" transport(ation) narrative persuade(-sion) Britishimperialism
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Developing a Data Modelling Tool to Visualize the Transformation of an ER Diagram into a Relational Schema
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作者 Elitsa Silyanova Arsova Silyan Sibinov Arsov 《Computer Technology and Application》 2012年第3期201-205,共5页
In this paper, the authors present the development of a data modelling tool that visualizes the transformation process of an "Entity-Relationship" Diagram (ERD) into a relational database schema. The authors' foc... In this paper, the authors present the development of a data modelling tool that visualizes the transformation process of an "Entity-Relationship" Diagram (ERD) into a relational database schema. The authors' focus is the design of a tool for educational purposes and its implementation on e-learning database course. The tool presents two stages of database design. The first stage is to draw ERD graphically and validate it. The drawing is done by a learner. Then at second stage, the system enables automatically transformation of ERD to relational database schema by using common rules. Thus, the learner could understand more easily how to apply the theoretical material. A detailed description of system functionalities and algorithm for the conversion are proposed. Finally, a user interface and usage aspects are exposed. 展开更多
关键词 E-learning course data modelling tool entity-relationship model relational model.
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Velocity Profiles between Two Baffles in a Horizontal Circular Tube 被引量:1
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作者 Tae-Hyun Chang Hae-Soo Lee +2 位作者 Keon-Je Oh Doeg Hee Doh Chang-Hoan Lee 《Journal of Thermal Science》 SCIE EI CAS CSCD 2014年第6期544-551,共8页
The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat.The baffles are also an important element inside the heat exc... The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat.The baffles are also an important element inside the heat exchanger.Internal materials influence the flow pattern in the bed.The influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular tube.The velocity of the particles was measured before the baffle and between them in the test tube.Results show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front baffle.The flows circulate in the front and rear baffles.These flow profiles are related to the Reynolds number(Re) or the flow intensity.The velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front wall.Swirling flow was employed in this study,which was produced using tangential velocities at the inlet.At the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without swirl.However,velocities between two baffles are not much different from those without swirl. 展开更多
关键词 BAFFLE Shell and tube Tangential inlet SWIRL Particle image velocimetry
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Dynamic mode decomposition of hairpin vortices generated by a hemisphere protuberance 被引量:8
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作者 TANG ZhanQi JIANG Nan 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第1期118-124,共7页
We present dynamic mode decomposition (DMD) for studying the hairpin vortices generated by hemisphere protuberance measured by two-dimensional (2D) time-resolved (TR) particle image velocimetry (PIV) in a water channe... We present dynamic mode decomposition (DMD) for studying the hairpin vortices generated by hemisphere protuberance measured by two-dimensional (2D) time-resolved (TR) particle image velocimetry (PIV) in a water channel. The hairpins dynamic information is extracted by identifying their dominant frequencies and associated spatial structures. For this quasi-periodic data system, the resulting main Dynamic modes illustrate the different spatial structures associated with the wake vortex region and the near-wall region. By comparisons with proper orthogonal decomposition (POD), it can be concluded that the dynamic mode concentrates on a certain frequency component more effectively than the mode determined by POD. During the analysis, DMD has proven itself a robust and reliable algorithm to extract spatial-temporal coherent structures. 展开更多
关键词 hairpin vortices hemisphere protuberance time-resolved particle image velocimetry dynamic mode decomposition proper orthogonal decomposition
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Fourier mode decomposition of PIV data. 被引量:6
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作者 MA LiQun FENG LiHao +2 位作者 PAN Chong GAO Qi WANG JinJun 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2015年第11期1935-1948,共14页
The modal decomposition technique is one of the most effective methods for studying the flow dynamics in a complex flow. By rejuvenating the discrete Fourier transform(DFT), this paper proposes a Fourier mode decompos... The modal decomposition technique is one of the most effective methods for studying the flow dynamics in a complex flow. By rejuvenating the discrete Fourier transform(DFT), this paper proposes a Fourier mode decomposition(FMD) method for the time series of particle image velocimetry(PIV) data from the fluid field. An experimental case concerning the control of the flow around a circular cylinder by a synthetic jet positioned at the rear stagnation point is used to demonstrate the use of the FMD method. In the three different regimes where the natural shedding frequency and actuation frequency dominate respectively or simultaneously, it is found that the FMD method is capable of extracting the dynamic mode along with its amplitude and phase according to the selected characteristic frequency based on the global power spectrum. For the quasiperiodic flow phenomena presented in this particular case, the FMD method can reconstruct the original flow field using the zero-th mode and the selected mode corresponding to the characteristic frequency. Similarities and differences between the FMD method and the dynamical mode decomposition(DMD) and proper orthogonal decomposition(POD) methods are also discussed. 展开更多
关键词 flow control vortex dynamics Fourier mode decomposition (FMD)
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