基于冗余提升小波包及Volterra级数的机械故障预测方法

针对Volterra级数模型在染噪时间序列预测中精度较低,以及收敛速度慢的关键问题,提出了一种基于冗余提升小波包(Redundant Lifting Wavelet Packet,RLWP)及Volterra级数的机械故障预测方法。首先用冗余提升小波包对振动信号进行分解,对分解得到的末层所有频带信号用奇异值分解进行降噪。然后通过构造二阶Volterra级数预测模型对降噪后的各频带信号进行预测。最后用冗余提升小波包重构算法对各频带预测信号重构,获得预测信号。仿真结果表明:结合冗余提升小波包的多分辨率分析及奇异值降噪,能明显提高Volterra级数模型的预测精度及收敛速度。在工程应用中该方法准确预测出了某离心压缩机的不平衡故障。     

基于小波分析和BP神经网络的股指期货价格预测

将小波分析与BP神经网络相结合,构建了股指期货价格预测模型。选取沪深300股指期货从上市日至2013年8月20日的收盘价格数据作为样本,运用sym8小波变换对数据进行降噪处理,分别运用降噪前后的数据对BP神经网络进行训练和检验。结果表明,降噪数据可以有效提高股指期货价格预测的效果。     

小波分解和ARIMA模型相结合的短期风速预测

风速时间序列的非平稳性使得对其预测比较困难。论文首先对风电场的小时平均风速数据采用基于传统的滚动时间序列模型进行短期预测,针对原始序列的非平稳性和异常点的干扰,利用小波分解理论对原始风速进行小波分解与重构,然后对重构后的概貌部分和细节部分分别采用ARIMA模型进行预测,累加结果得到未来时段的预测风速,经比较分析可知,小波ARIMA模型的预测效果优于传统的滚动时间序列模型的预测效果。     

基于小波与DBN的负荷预测模型

针对原始数据存在干扰以及BP神经网络和深度置信网络(DBN)局限性的问题,提出了一种小波与DBN相结合的负荷预测模型.该方法主要是先将原始负荷数据进行小波降噪,将降噪后的数据用来训练DBN模型,最后用该模型进行负荷预测.分别对比BP、DBN以及小波与DBN组合模型对负荷的预测结果与真实值的差异,仿真结果表明小波与DBN组合预测模型预测曲线趋势和真实值的一致性最好,从数据中得出BP、DBN以及组合模型预测结果的均方根误差分别为23.862、13.656和10.477,说明小波与DBN组合模型对负荷预测的准确性最高.     

小波在金融时序预测中的应用

利用小波函数的局部化性质,对非平稳时间序列股票开盘价数据进行分解,然后再进行M allat重构。这样就得到了原始数据的近似信号,再应用传统时间序列预测方法ARMA（p,q）模型对重构后的数据进行预测,将预测结果与实际值进行比较,可得小波分析方法预测效果比较理想。     

小波变换和DGM(2,1)模型在昆明市人口预测中的应用

对于昆明市人口呈不均匀的增长趋势,传统的灰色预测方法并不能取得很好的预测效果.将小波变换与DGM(2,1)模型相结合,利用小波变换去除原始序列中的噪声,将非光滑的原始序列转化为相对光滑的新序列,然后通过DGM(2,1)模型对新序列进行预测,可以得到较为满意的预测效果.以2006—2014年的昆明市人口数据为基础,预测2...     

基于基线漂移校正的旅行时间预测模型

路段旅行时间及其预测值是管理部门实施交通流组织,提供交通信息服务的重要依据,也是出行者合理选择出行路径的重要参考.文中基于浮动车检测数据研究了路段旅行时间的计算算法及数据预处理方法;分析了旅行时间序列中的基线漂移现象,并运用小波分析法给出了基线漂移的校正方法以达到对时间序列降噪处理的目的;最后,基于自回归移动平均法建立了路段旅行时间的预测模型,并选取实际数据验证了文中模型的有效性和精确性.     

混沌时间序列的自适应正交小波神经网络预测

针对非线性混沌时间序列预测问题,提出一种基于正交小波神经网络的自适应预测算法.根据来自非线性序列模型的期望输入输出数据,利用小波框架理论建立初始的小波神经网络.采用正交化逐步选择方法对于初始小波神经网络进行结构优化,从而建立最精简的网络模型.同时引入在线学习算法在线修改网络权值和小波神经元的参数,从而提高模型的自适应能力和泛化能力.通过对时滞Mackey-Glass超时间序列和时变Lorenz混沌序列的预测,证明了算法的有效性.     

原子钟数据的改进经验模态分解降噪

为了提升原子钟数据降噪效果,基于经验模态分解(EMD),结合小波阈值降噪方法,提出了一种改进EMD的方法.在分析原子钟噪声模型的基础上,明确了原子钟频率数据非线性、非平稳的特点.结合EMD方法原理中固有模函数(IMF)需要满足的条件和提取步骤,利用窗口做出划分,对每一个窗口进行降噪处理,再利用小波阈值进行二次降噪,最后...     

基于小波分析的全国社会消费品零售总额时间序列预测

选取2003年1月到2010年3月的全国社会消费品零售总额数据,运用小波分析及Mat-lab,SPSS软件,分析了中国近几年社会消费品发展的变化趋势,用小波方法对原始数据进行消噪、阈值化处理后进行重构,使得消噪后数据更能反映其本质及变化规律,用ARIMA时间序列模型进行建模预测,并作出了实证分析.     

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     

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