一种改进的FCM聚类算法的混合矩阵估计

在增强信号稀疏性的基础上,对模糊C均值(fuzzy C-means, FCM)聚类算法进行改进,达到提高混合矩阵估计精度的目的,更好地解决欠定盲源分离问题。主要针对稀疏成分分析理论"两步法"中的混合矩阵估计算法改进,提出一种基于隶属度划分优化的FCM聚类算法。通过改变目标函数中的隶属度划分方式,来影响数据的归类,从而决定了混合矩阵中元素的估计精度。最后,将改进的算法用于语音信号仿真实验,完成混合矩阵估计。实验结果表明,用改进的算法所获得的矩阵估计误差小且精度高,可使归一化均方误差减小1.3 dB,角度偏差最多可减小1°。     

一种基于网格划分的模糊聚类算法

提出了一种改进的模糊聚类算法GBFC(Grid—Based Fuzzy Clustering)．在定义隶属度函数前先做网格划分，形成数据簇的基本形状，并提供真实的参数信息参与此后的隶属度函数定义．隶属度函数综合考虑了影响簇形状的因素，具有合理直观的几何意义且形式简洁．算法通过网格划分加速聚类过程，通过模糊隶属度函数容忍噪声数据，克服了传统模糊聚类算法时间耗费量大的缺点．实验表明该算法具有良好的聚类性能．     

一种改进的基于FCM的目标跟踪数据关联算法

为了克服杂波环境下对多目标进行数据互联时,计算量出现组合爆炸现象,提出了改进的基于FCM的多目标跟踪数据关联算法.将航迹的预测值转换到各个传感器的观测空间作为各自的聚类中心,利用目标属于所有量测的隶属度,来代替JPDAF中的关联概率,将多目标数据关联问题可转化为模糊聚类问题,进行关联计算.改进的基于FCM的多目标跟踪数据关联算法,有效地利用了目标状态估计中的历史信息,实现量测与航迹的关联.该算法克服了JPDAF算法计算量大的缺点,实现杂波环境下多目标数据互联.仿真结果表明了该算法的有效性.     

基于高斯隶属度的包容性指标模糊聚类算法

基于传统的模糊聚类算法(C-means、FCM),在高斯隶属度函数的基础上给出了包含性指标的定义,提出了基于高斯隶属度的包容性指标模糊聚类算法(fuzzy inclusion-based clustering,FIC)。该方法通过获取高斯隶属度函数的包含性指标,为每个分类确定一个支持距离的半定性矩阵,来保证每个分类到所有数据类的距离和与所有数据类包含度的总和一致。通过UCI中Wine数据集进行了仿真实验,实验结果表明与FCM算法相比较,FIC算法具有更好的有效性和可行性。     

新课程改革以来中学生物学教学研究的文献计量学分析

空间聚类是空间数据挖掘和知识发现的的主要方法之一."基于模糊C均值的空间聚类方法"可以广泛地应用到对空间数据挖掘和知识发现中的分类分级研究.该方法的基奉思想是:首先,设定聚类数目和模糊度常数,并初始化各个聚类中心,每一个数据点按照一定的模糊隶属度隶属于某一聚类中心;然后,逐步进行循环迭代.改变目标函数值以及各个隶属度,并决定新一级聚类中心;最后,当日标函数收敛或者数据点的隶属度保持恒定时,就得到了输入数据的最终聚类中心,从而完成了模糊聚类划分.该文给出了该方法的实现步骤,并以实例验证了方法的可行性和科学性,取得了很好的效果.     

基于样本模糊隶属度归n化约束的松弛模糊C均值聚类算法

模糊C均值聚类算法(FCM)由于样本模糊隶属度归一性的约束,导致FCM算法对噪声数据敏感。提出松弛模糊C均值聚类算法(RFCM),RFCM算法在可能性C均值聚类算法(PCM)目标函数的基础上,放弃了FCM算法单个样本模糊隶属度归一化约束,转为n个样本模糊隶属度之和为n的约束;并利用粒子群算法对样本模糊隶属度进行优化估计,使得模糊指标可拓展为m0的情况,同时采用梯度法得到RFCM算法聚类中心迭代公式。RFCM理论分析了算法对噪声数据抗噪的原理,解释了RFCM算法模糊指标m0的合理性,讨论了RFCM算法的收敛性。基于Gauss数据集和UCI数据集的仿真测试验证了所提出算法的有效性。     

松弛模糊C均值聚类算法*

模糊c均值聚类算法(FCM)由于样本模糊隶属度归一性的约束,导致FCM算法对噪声数据敏感。提出松弛模糊C均值聚类算法(RFCM),RFCM算法在可能性c均值聚类算法(PCM)目标函数的基础上,放弃了FCM算法单个样本模糊隶属度归一化约束,转为n个样本模糊隶属度之和为n的约束,并利用粒子群算法对样本模糊隶属度进行优化估计,使得模糊指标可拓展为m>0的情况,同时采用梯度法得到RFCM算法聚类中心迭代公式。RFCM理论分析了算法对噪声数据抗噪的原理,解释了RFCM算法模糊指标m>0的合理性,讨论了RFCM算法的收敛性。基于gauss数据集和UCI数据集的仿真测试验证了所提出算法的有效性。     

数据分类的两步矩阵投影算法

化工过程的数据分类是进行数据校正和协调计算的基础。常用的两层次矩阵投影变换算法在对未测数据进行分类时,可能无法识别出所有的不可估计型数据。为了准确地将可估计型和不可估计型数据分开,采用Crowe等人提出的投影矩阵,引入矩阵的绝对线性无关列的概念,提出了新的数据分类方法。数学推导证明,此方法对化工过程未测数据分类彻底,并用一个示例将新旧算法对未测数据的分类结果进行了对比,验证了新算法作数据分类的正确性。     

分布式环境下全局模糊频繁项目集的快速挖掘

为了解决模糊关联规则挖掘算法需要用户事先给定模糊集和相应隶属度函数的问题,提出基于分布式聚类自动生成模糊集及隶属度函数的算法GFAM.该算法利用分布式K-Means聚类算法对每个数值型属性进行聚类,求得聚类中心,由此构造全局模糊集,定义全局隶属度函数.DFAR算法根据构造的全局模糊集及隶属度函数进行分布式模糊频繁项目集的快速挖掘,采用全局-局部站点模式,其中包括局部模糊频繁项目集产生算法FLF和全局模糊频繁项目集产生算法FGF.实验结果表明,该算法能准确地生成全局模糊频繁项目集,在求解全局模糊频繁项目集过程中,传送局部模糊候选项目集支持数的通信量为O(n),提高了算法的挖掘效率.     

基于矩阵特征值分析的模糊聚类有效性指标

许多有效性指标已经被提出量化地估计和评价模糊聚类算法对于给定数据集的划分结果.但是由于不合理的结构和极大的时间耗费,迄今这些有效性指标几乎都无法满足应用的一般性需求.为此,提出一个基于Gerschgorin圆盘定律估计的聚类有效性指标来估计模糊聚类的类数.先由模糊聚类划分的结果得到一个相关性矩阵,接着求出该矩阵的所有特征值和特征向量,然后基于经典Gerschgorin圆盘定律估计最优的类数.为了检验提出的指标在模糊聚类中的有效性,把模糊聚类算法应用到带有不同特征的3个人工数据集和3个真实的数据集,并比较提出的指标和2个最常用的模糊聚类有效性指标.实验结果证明了所提出的有效性指标能够发现被聚类数据集的固有结构,从而得出更加准确的类数.     

Markedness and its Interpretation in Language Use

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.     

Features of Women's language

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.     

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.     

Achieving Unusual States of Matter Under High Pressure

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-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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