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1.
根据粗糙集的理论,在信息系统中使用了分布约简的概念,并利用相应的可辨识属性矩阵,提出了一种在决策表中获取规则的增量式方法,该算法对决策表中出现的各种新对象进行分析,在原有的分布约简的基础上进行增量式更新,从而避免了重新计算.  相似文献   

2.
基于遗传算法和粗糙集理论的增量式规则获取方法   总被引:1,自引:0,他引:1  
规则获取的增量式算法是数据挖掘领域的一个热点问题.基于粗糙集理论,从规则获取和优化两方面研究了基于遗传算法的增量式规则挖掘方法,它具有结构简单、搜索效率高、求解速度快等优点.通过研究决策表和决策规则系数,建立基于粗糙集表示和度量的知识,并且将遗传算法和规则挖掘算法相结合,建立了新的优化方法,提出了一种基于遗传算法的增量式规则挖掘的方法.在原有规则集的基础上进行规则和规则参数的增量式更新,避免了为更新规则而重新运行规则获取算法.试验结果表明,执行增量式GA的能够有效地获取最优规则.  相似文献   

3.
基于可变精度粗集模型的增量式规则获取算法   总被引:4,自引:0,他引:4  
为了获取最小决策规则集,当增加新样本时,传统的方法通常需要对决策表中所有数据重新计算,效率欠佳。从可变精度粗集模型理论出发,讨论了新增记录与已有条件属性等价类的关系及对规则集的影响,在此基础上提出了基于可变精度粗集模型的增量式规则获取算法。通过仿真实验表明,这种增量式算法是可行的。  相似文献   

4.
基于可变精度粗集模型的增量式规则获取算法   总被引:1,自引:0,他引:1  
为了获取最小决策规则集,当增加新样本时,传统的方法通常需要对决策表中所有数据重新计算,效率欠 佳.从可变精度粗集模型理论出发,讨论了新增记录与已有条件属性等价类的关系及对规则集的影响,在此基础 上提出了基于可变精度粗集模型的增量式规则获取算法.通过仿真实验表明,这种增量式算法是可行的.  相似文献   

5.
基于增量式遗传算法的粗糙集分类规则挖掘   总被引:8,自引:0,他引:8  
从规则获取和优化两个方面研究了基于遗传算法(GA)的增量式粗糙集分类规则挖掘方法.通过研究决策表和决策规则系数,建立了基于粗糙集表示和度量的知识理论,将GA和粗糙集分类规则挖掘算法相结合,在保持原有知识完备的前提下,利用GA对以增量形式获得的分类规则进行优化,获取最优分类规则.试验结果表明,执行增量式GA所需时间较执行一般GA所需时间要少,可有效完成分类规则优化的任务,同时还可提高分类的精度,使分类结果具有更好的可理解性.  相似文献   

6.
本文文讨论分析信息系统(或决策表)新增对象的各种情况,提出一个直接、简洁基于差别矩阵的属性核增量式更新算法.该方法在更新差别矩阵时仅须插入某行或某列,或者删除某行或采列,有效地提高核的更新效率.  相似文献   

7.
关联规则增量式更新算法   总被引:1,自引:0,他引:1  
讨论了关联规则的更新问题,对关联规则的增量式更新算法IUA进行了分析,指出了其存在的问题和出现问题的原因,提出了一种改进的关联规则更新算法UA.对各种情况下关联规则的更新问题进行了讨论,说明了其均可以转化为数据库不变、支持度改变的情况来讨论,UA算法在充分利用原有信息的基础上,提高了算法的效率。  相似文献   

8.
讨论了关联规则的更新问题。对关联规则的增量式更新算法——IUA进行了分析,指出了其存在的问题和出现问题的原因,提出了一种改进的关联规则更新算法-UA。对各种情况下关联规则的更新问题进行了讨论,说明了其均可以转化为数据库不变、支持度改变的情况来讨论。UA算法在充分利用原有信息的基础上,提高了算法的效率。  相似文献   

9.
增量式更新算法能充分利用已挖掘出的知识来提高挖掘效率,是数据挖掘高效算法研究中一个主要方向.本文首先分析了经典的关联规则增量式更新算法FUP(Fast Updating algorithm)算法的不足,提出了一种改进的关联规则增量式更新算法IIUA(Improved Incremental Updating Algorithm),极大地降低了存储空间和挖掘时间需求,从而提高了整个关联规则挖掘的效率.  相似文献   

10.
提出了基于Rough集理论的车牌字符识别方法。该方法根据训练样本的特征向量建立决策表,应用Rough集理论对决策表属性进行约简,从约简后的决策表中获取决策规则,按照规则可信度的大小进行规则的匹配。实验表明该方法有效减少了决策属性的个数,提高了规则的泛化程度,简化了规则匹配算法,在车牌字符识别中取得了较好的识别效果。  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.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
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   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
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