润滑材料智能分析系统中BP神经网络权值的优化

探讨了运用遗传算法对润滑油智能分析系统中神经网络的连接权值的优化.在预先对网络结构进行优化后,对随机产生的网络权值及阈值进行编码,利用多种不同的初始连接权值分别对每个网络进行训练,利用误差函数确定适应度函数,利用交叉、变异等遗传操作算子对群体进行处理,从而得出最佳网络权值和阈值.     

改进的暂态混沌神经网络多用户检测器

提出了一种基于自反馈连接权值优化策略的暂态混沌神经网络多用户检测方法.该方法采用一种改进的变指数退火函数,对自反馈权值进行优化,既充分利用混沌的动态特性进行搜索,使算法可以从局部最优值中跳出,又加快收敛速度,减少收敛时间.仿真结果表明,这种检测器在误码率和抗远近效应方面优于已有的神经网络多用户检测器,能较好地逼近最佳多用户检测器的性能.     

多层前向小世界神经网络的逼近与容错性能

基于Watts-Strogatz网络模型的构造思想,对多层前向神经网络中的规则连接依重连概率进行重连,构建了一种多层前向小世界神经网络模型.对该网络模型进行简要的数学描述,并以函数逼近和网络容错仿真考察了构建的小世界神经网络的性能.结果表明,与规则或随机连接的网络相比,当重连概率处于0.1～0.2时,小世界神经网络具有更优的逼近性能,且当网络学习速率参数在0.1～0.3之间时,对小世界神经网络的逼近性能影响较小.此外,当网络权值故障率小于30%时,重连概率不大于0.8的小世界神经网络与规则网络同样具有较优的容错性能,而当故障率大于40%时,重连概率较大的小世界神经网络和随机连接的神经网络的容错性能要明显优于规则网络.     

子波基神经网络及其建模

将神经网络与子波理论结合,构成新型的神经网络结构-子波基神经网络,不同于一般前向神经网络的是该网络的隐层单元的激活函数为不同尺度下的子波函数.该网络具有良好的逼近非线性的能力.本文将其应用于非线性系统建模.     

基于遗传算法和BP算法的混合算法

结合神经网络的优化问题,提出一种新的混合算法.该算法是在遗传操作中嵌入BP算子,有效地结合了遗传算法全局寻优与BP算法快速收敛的特点,同时采用二进制编码和实数编码将神经网络的结构与权值混合编码到串中,实现了结构与权值的同步优化.仿真结果表明,新算法既能够快速地收敛到全局最优解,又能够在简化网络结构复杂度的同时得到网络权值的最佳逼近.     

防止BP神经网络训练函数进入局部误差振荡缺陷的一种方法

在应用MATLAB软件神经网络工具箱函数训练获取BP神经网络权值矩阵函数或非线性数学模型时,由于BP神经网络训练样本集中输入、输出(目标)样本参数的绝对值和离散性有时太大或过于集中,在网络权值矩阵误差函数逼近过程中,易产生局部误差最优或误差振荡等缺陷。本文介绍一种利用MATLAB神经网络工具箱prestd和poststd函数,通过对输入、输出(目标)样本参数进行正规化处理,使其不至于太小,可防止在网络权值矩阵函数训练时不会进入局部误差最优或误差振荡的缺陷区域。经实例分析计算证明,该方法在如何优化获得实用可靠的BP神经网络权值矩阵函数是有效可行的,对研究MATLAB语言用于网络系统控制和非线性函数或数学模型逼近研究工程技术人员具有一定的参考价值。     

基于改进的双并联动态过程神经网络的旅游需求预测

为克服前向过程神经网络收敛速度慢、精度低的问题,提出了一种改进的双并联动态过程神经网络,对于给定的全连接的过程神经网络,通过优化其连接权值和网络结构,删除冗余连接使之成为部分连接的过程神经网络系统,并给出了基于正交基函数展开的学习算法,从而降低了计算的成本。改进的双并联动态过程神经网络应用于旅游预测问题,结果表明其预测精度能够满足工程需要。     

基于有跨越连接的多层神经网络的优越性

分析神经网络结构的各种连接方式,提出多层神经网络的一般结构．研究表明,有跨越连接的神经网络可以逼近神经网络理想状态,说明了跨越连接神经网络的优越性．     

非线性系统建模的复合型模糊神经网络研究

针对非线性系统建模问题,提出了一类由函数逼近和规则推理网络构成的复合型模糊神经网络,其规则网络基于过程先验知识用于对操作区间的划分,而函数网络采用改进型模糊神经网络结构完成非线性函数逼近。采用一类非线性函数模型进行了仿真研究,结果表明,复合型模糊神经网络较之普通模糊神经网络在建模收敛速度和预测精度等方面都有较大的改善。     

基于免疫进化策略的神经网络优化方法

对神经网络的研究多年来主要集中于网络权值优化或结构优化上,却忽略了神经网络结构与权值之间密不可分的联系.针对上述问题,将免疫系统中的浓度机制和记忆机制引入进化策略,提出了一种基于免疫进化策略的神经进化算法,在优化网络拓扑结构的同时优化网络的连接权值.进一步地,用Cauchy变异算子代替传统的Gauss变异算子,以获得更为理想的全局收敛效果.理论分析和仿真结果表明,免疫进化策略能够很好地保持种群多样性,避免未成熟收敛,采用免疫进化策略设计神经网络具有良好的全局收敛性能和快速学习网络结构和网络权值的能力.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

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     

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