数据挖掘中一种基于集合覆盖的元素重要性估计算法

对给定数据集合的元素重要性进行估计是数据挖掘领域中的一项重要应用。现有的技术都是通过排序或选择来发现重要元素,其主要缺点是没考虑高排名对象可能非常相似甚至完全相同这一事实,忽略了高排名对象间的冗余性。因此,在强调多样性的场合,该方法性能有限。本文通过将排序和选择相结合,提出一种基于集合覆盖的元素重要性估计算法。该算法不仅考察单个集合覆盖的解,而且计算元素参与的高质量集合覆盖数量,进而为元素分配重要性分值。基于实际数据的实验和用户学习结果表明,本文算法性能高效,元素重要性评估结果的有用性高,且与人类感知相一致。     

遍历从N个相异元素中取M个元素可能排列的新算法

给出了遍历从N个相异元素中取M个(N≥M)元素可能排列的新算法．新算法中放弃了首先将全部可能节点进行字典排序，然后按序逐个生成的传统思想，实现了每进行一次数据交换即产生一个新节点，从而极大地提高了遍历的效率。     

遍历从N个元素中取M个元素可能组合的最佳算法

从N个相异元素中取M个元素(M≤N)的可能组合的遍历问题是组合数学中重要的基础性问题．关于该问题的现行算法是建立在对于搜索到的每一个节点的诸元素首先进行排序，然后搜索下一个节点．本文对于该问题给出一个全新的算法．新算法中放弃了对于节点诸元食的排序，实现每进行一次数据交换即搜索到一个新的节点，因而成为解决该问题的最佳算法．使用该算法编辑计算机程序，有编程简短、占用机器内存小的特点。     

基于PAC算法的流数据Top-k实时查询

针对流数据的Top-k查询问题,为降低对存储容量和处理时间的要求,利用概率近似正确(PAC)原理,提出了一种实时查询算法,通过随机抽样近似地估计流数据中最大的k个数据,并保证误差和可信度均在规定的范围内.该算法设置k个随机独立排序器,每个排序器独立地抽取N个数据并返回各自不同的最大值d,然后用这k个最大值排序获得该流数...     

可变阈值因子的快速自适应门限检测算法

针对基于排序类自适应门限算法运算量大的问题,提出了利用可变的第k小元素替代排序类噪声能量估计的快速自适应门限检测算法.其中对第k小元素的取值仅采用快速排序算法的少次迭代过程,不须要排序完整的检测统计量,可实现快速噪声能量估计,以此作为自适应门限的参变量,结合相应的可变阈值因子达到快速自适应门限判决检测的目的.分析了检测概率和虚警概率以及运算复杂度,仿真对比了该算法与排序类自适应门限算法检测概率和虚警概率.结果表明:当有信号发送时,该算法与排序类检测算法检测概率基本一致,虚警概率有所减小;当没有信号发送时,相同阈值因子情况下,随着k值的增大,虚警概率越来越小.     

一道难题征解的简证及引申

浙江师大主办《中学数学教研》1992年第10期上有如下一道难题征解:28*　设N为自然数集,N0,1为由数字0和1组成的所有正整数的集合.证明或否定:对a∈N,b∈N,有ab∈N0,1.下面利用集合中元素的无穷性构造b给出一个简证.证明　令M={n|n=10i,i∈N}N0,1,显然为无穷集.a∈N,M中的每个元素用a取模,分成a个子集,其中第k个表示为:Ma,k={s|s∈M,k=s(moda),(0≤k≤a-1)}(1)若Ma,0非空,则结论显然成立;(2)若Ma,0为空集,则Ma,1,Ma,2,…,Ma,a-1中至少存在一无穷集,否则,M将为有穷集,矛盾.不妨设Ma,k为无穷集.从Ma,k中任取a个两两互不相同的元素10im(…     

随机P-集合的数据筛选过滤

在随机P-集合概念的基础上,给出了基于随机P-集合的数据生成,提出了基于随机P-集合的数据筛选-过滤粒度定理、数据筛选-过滤剩余定理和数据筛选-过滤恢复定理等,并给出基于随机P-集合的数据筛选-过滤在医疗诊治系统中的应用。     

dGridTopk-FCPM:一种基于模糊理论和d-网格的Top-k空间co-location模式挖掘方法

空间co-location模式是指在空间中相互邻近且频繁出现的空间特征的集合。由于传统的co-location模式挖掘使用单一的距离阈值来定义空间邻近关系,忽略了距离变化对空间邻近关系带来的影响,并且最小频繁度阈值的设定对于没有数据相关专业知识的用户来说存在一定的困难。针对上述问题,该文提出了一种基于模糊理论和d-网格的邻近隶属度计算方法,该方法可以避免计算Euclid距离并且可以利用d-网格快速找到满足模糊邻近关系的极大团,然后结合Top-k思想,挖掘出频繁度最大的k个空间co-location模式。实验结果表明:该方法具有更高效的性能和更细致的计算结果,并且通过比较召回率,发现该方法得到的频繁度最大的k个模式与传统co-location模式挖掘算法得到的频繁度最大的k个模式大部分相同,说明提出的模糊度量和挖掘算法具有较大的实用价值。     

基于LARPBS模型的快速并行归并排序算法

提出了一种基于LARPBS模型上的并行归并排序算法,该算法使用M1 ε(0<ε<1)个处理器可以在O(lb lbM)时间内对Mε个有序序列进行归并.利用该归并算法对长度为N的序列进行排序,使用N1 ε个处理器可以在O((lb lb N)2)时间内完成.     

一种采用过滤技术的Twig查询算法

提出一种采用过滤技术的Twig查询算法TwigFilter:通过设计一种过滤算法,过滤掉所有与查询结果无关的元素;给出一种查询算法,实现对过滤后剩余元素的快速查询.在不同数据集上实验证明,提出的算法对于提高Twig查询处理性能是有效的.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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