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151.
基于概念格的规则产生集挖掘算法 总被引:27,自引:0,他引:27
传统的规则提取算法产生的规则集合相当庞大,其中包含许多冗余的规则.使用闭项集可以减少规则的数目,而概念格结点问的泛化和例化关系非常适用于规则提取.基于概念格理论和闭项集的概念,提出了一种新的更有利于规则提取的格结构,给出了相应的基于闭标记的渐进式构造算法和规则提取算法.最后提供给用户的是直观的、易理解的规则子集,用户可以有选择地从中推导出其他的规则.实验表明该方法能够高效地挖掘规则产生集. 相似文献
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Minjie Xie 《中兴通讯技术(英文版)》2012,(2):25-33
Lattice vector quantization(LVQ) has been used for real-time speech and audio coding systems.Compared with conventional vector quantization,LVQ has two main advantages:It has a simple and fast encoding process,and it significantly reduces the amount of memory required.Therefore,LVQ is suitable for use in low-complexity speech and audio coding.In this paper,we describe the basic concepts of LVQ and its advantages over conventional vector quantization.We also describe some LVQ techniques that have been used in speech and audio coding standards of international standards developing organizations(SDOs). 相似文献
156.
Rough set theory is a useful tool for dealing with imprecise knowledge. One of the advantages of rough set theory is the fact that an unknown target concept can be approximately characterized by existing knowledge structures in a knowledge base. This paper explores knowledge structures in a knowledge base. Knowledge structures in a knowledge base are firstly described by means of set vectors and relationships between knowledge structures divided into four classes. Then, properties of knowledge structures are discussed. Finally, group, lattice, mapping, and soft characterizations of knowledge structures are given. 相似文献
157.
A general class of consensus measures of fuzzy sets is introduced in this paper. It is shown that, while the consensus measures are valuations but neither isotone nor antitone with respect to the lattice structure induced by the pointwise maximum and minimum operations to the set of all the fuzzy sets on a nonempty crisp set, they are antitone valuations with respect to the lattice structure induced by the generalized sharpening relation to a quotient set of the set of fuzzy sets. It is also shown that the solutions of a finite fuzzy relation equation that have the maximum consensus measure can be characterized through the join operation of the latter lattice in terms of the maximum solution and some of the minimal solutions of the equation. 相似文献
158.
The purpose of the present paper is testing an in‐house efficiency algorithm based on lattice Boltzmann method (LBM) and using it to resolve the obtained coupled nondimensional governing equations to analyze two‐dimensional free convection inside a cold outer cavity subjected to a heated cylindrical diamond array. Steady state or oscillatory results are obtained using the Bhatnagar‐Gross‐Krook collision model associated to the thermal LBM. Both the velocity and temperature fields are solved using the D2Q9 models. With different Rayleigh numbers (Ra), the tested free convection can either achieve to steady state or oscillatory. We extended our in house Fortran 90 code using curved boundary conditions and implemented them into a cavity with a diamond array. The numerical simulations were done using distinct Ra (106 and 10 7) and distances between the four neighboring circular cylinders aligned in a diamond array. The effects of several physical parameters, including Ra and position of the hot body array on flow and heat transfer characteristics are investigated. The obtained results are highlighted in the form of streamlines, isotherms, and velocities plots. We show in this paper the stability and the efficiency of the LBM to deal with a complex geometry and its ability to reach suitable convergence criteria for high Ra (10 6 and 10 7). The numerical results indicate that LBM can simulate numerical problems with a high Ra reaching a steady state where we can depict the change of the flow pattern and enhancement of the heat transfer in the presence of heated diamond array. 相似文献
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《钢铁研究学报(英文版)》2016,(8):828-833
One assumption underlying the conventional dilatometric analysis based on the lever rule is that the volume of the specimen changes isotropically during phase transformation,which conflicts with the irreversible length change shown in actual measurements.The contribution of this irreversible effect to the dilation data of pure iron up-on heating and cooling was respectively quantified via conversion equations based on lattice parameters.A model con-sidering the elastic strain and creep deformation was established for both the interpretation of the irreversible volume change and the discrepancy between the results measured by a dilatometer and a micrometer. 相似文献