首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
针对高维数据包含的不相关和冗余特征影响检测方法性能的问题,提出了集成filter和wrapper方法的混合特征选择新方法.采用基于信息增益的filter方法,删除不相关特征;采用基于改进的自适应遗传算法和评价函数的wrapper方法,获取最优特征子集.在入侵检测中的应用表明,该方法能降低特征选择的时间,检测率和虚警率均优于其它方法.  相似文献   

2.
通过删除数据集中的无关属性和冗余属性构建的选择性分类器可以有效地提高分类精度和效率.由于处理不完整数据的复杂性,已有的选择性分类器大都是针对完整数据的.然而,现实中的数据通常是不完整的并且包含许多冗余属性或无关属性.为解决这一问题,在构建的不完整数据分类器DBNB的基础上给出了一种有效的选择性分类器:SDBNB.在12个标准的不完整数据集上的实验结果显示,SDBNB的分类准确率比分类效果较好的选择性不完整数据分类器SNB和SRBC平均高出0.69%和0.58%,而其标准离差比SNB和SRBC平均低0.11和0.05.这表明SDBNB不仅有较高的分类准确率,而且分类效果更稳定.  相似文献   

3.
针对特征选择中Filter与Wrapper方法分别存在的问题,本文提出了一种新的基于分类互补性分析的特征选择算法.该方法将Filter方法与Wrapper方法结合起来.先根据ReliefF评估和对称不确定性评估去除不相关特征,再使用对称不确定性评估去除冗余特征,最后使用基于分类互补性分析的Wrapper特征选择算法选出最后的目标子集.实验表明该算法结合了Filter与Wrapper两者的优点,具备了高准确性,同时可以减少时间开销.文章最后在数字乳腺图像肿块的检测中应用了该算法,得到了良好的效果.  相似文献   

4.
针对矿用通风机常见故障展开研究,分析了转子不对中、不平衡、油膜涡动、喘振等故障的产生机理及故障表征,设计了基于粗糙神经网络的故障诊断系统。首先针对通风机故障类型特点进行故障数据采集,包括振动信号和温度信号。然后,预处理后的样本数据采用粗糙集的方法进行属性约简,删除冗余属性。最后,样本数据被分成训练样本和测试样本,分别用来训练和测试神经网络分类机。实验表明,该系统运行可靠、诊断率高,提高了通风机系统的安全性,拓展了粗糙集的应用范围。  相似文献   

5.
根据排序问题的单调先验知识,无监督学习问题中的观测属性之间也具备单调关系;否则该属性与排序无关,为冗余属性.基于排序互信息反应的两属性之间的单调关系,提出用每个属性与其他属性之间的平均互信息,来衡量每个属性与排序学习的相关程度,具有最高的平均互信息即为排序最相关的属性.  相似文献   

6.
一种基于属性依赖的属性约简算法   总被引:1,自引:0,他引:1  
针对现有属性约简算法存在的问题,利用信息论和粗糙集理论,提出了基于属性依赖的属性约简算法,该算法不用求核.首先利用单个条件属性与决策属性的依赖度来选择条件属性,取与决策属性依赖度大的属性,计算完毕后,将得到的条件属性两两之间进行依赖度计算,删除冗余属性,最后得到条件属性的约简.理论分析及实验结果表明该算法具有较好的约简效果及更高的运行效率.  相似文献   

7.
洪月华  徐霜  梁家荣 《广西科学》2013,20(2):128-131,136
为了实现对无线传感器网络监测得到的高维冗余且不确定的数据进行分类识别,提出一种由遗传算法和粗糙集进行优化的BP神经网络数据分类器模型,并形成了数据挖掘分类算法。该模型通过粗糙集理论的属性约简算法删除训练样本的冗余属性,利用遗传算法对神经网络的权值和阈值进行优化,并进行神经网络学习。数据挖掘分类算法学习速度快,能够有效提高无线传感器网络中数据的分类效率。  相似文献   

8.
为解决神经网络算法中样本数据包含大量与目标数据无关的属性而导致网络训练时间长、效率低的问题,提出基于改进模糊k均值(FKM)和BP神经网络算法的数据挖掘模型.利用改进的FKM聚类算法对输入数据的属性进行聚类,摈弃与目标属性相关性弱或冗余的属性,保留相关性强的属性,减少了神经网络的训练样本数据量,提高了网络的训练效率.对儿童血红蛋白含量的预测结果表明,该模型具有很好的实用性和可靠性.  相似文献   

9.
为保障油料供给的安全性,研究无线传感器网络(WSN)节点故障诊断的可行性策略,提出变精度粗糙集(VPRS)和RBF神经网络结合的故障诊断方法.该方法由运行中的汇聚节点实时获取子节点故障征兆,建立初始决策表,利用VPRS作为前端处理系统,对初始决策表进行约简,删除冗余的、不重要的属性征兆,并将约简后的结果输入RBF神经网络实现节点故障识别.仿真实验结果表明:对于具有显著不确定性的WSN节点故障诊断,该方法能够准确快速地得出诊断结果,鲁棒性和适用性更强.  相似文献   

10.
针对当前LEM2系列算法提取规则的效率和质量不高的问题,提出了基于广义决策函数的改进LEM2算法(GLD-LEM2).该算法根据广义决策函数来计算候选属性-值对集T(G),通过删除冗余属性-值对来逐步缩小T(G)的规模,以提高规则提取的效率;同时,根据广义决策函数相交最小原则来选择属性-值对,优先提取最简规则,以提高获取规则的质量.实验结果表明,对于完备或不完备的决策表规则,GLD-LEM2算法均能有效地提高规则提取的效率和质量.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号