最优组合预测及其在瓦斯浓度预测中的应用

瓦斯浓度预测是预防煤矿瓦斯事故的关键技术之一,以预测误差平方和最小为准则确定最优组合预测模型中的权系数,实现瓦斯浓度预测模型的最优组合,利用实际数据、通过与单一时间序列模型、线性回归模型及人工神经网络模型的预测精度对比分析,验证了瓦斯浓度最优组合预测模型的有效性和实用性。     

基于变分模态分解的瓦斯浓度多尺度组合预测

为提高煤矿瓦斯浓度的预测精度，将瓦斯浓度序列变分模态分解后对各模态分量分别采用差分整合移动平均自回归（ARIMA）模型和门控循环单元（GRU）模型进行预测，采用诱导广义有序加权函数平均（IGOWFA）算子组建变权组合预测模型的方法，对实验数据比较，结果表明：与采用单一预测方法或固定权值组合预测方法相比该方法的预测结果具有更高的预测精度，为煤矿判断瓦斯事故发生概率提供依据。     

组合预测模型构建及在合肥市PM2.5浓度预测中的应用

Dice系数是衡量两个序列接近程度的指标,将广义诱导有序加权平均(GIOWA)算子和Dice系数相结合,提出了基于GIOWA算子和Dice系数的组合预测模型,并且给出了优性组合预测的定义。将该模型应用到合肥市PM_2.5浓度预测上,选取2014-2021年共84期的PM_2.5浓度及核心影响要素的月度数据进行分析,将组合预测结果与单项预测结果进行对比,并分析了组合预测模型中参数取值发生变化时对组合预测权重、预测效果评价指标和Dice系数影响情况。实证结果表明所建立的组合预测模型的预测效果要优于单项预测模型。     

大气污染预测的参数化组合算子方法

大气污染物浓度预报是一个多因素、复杂的非线性问题，以往多使用线性回归方法．根据Zimmermann提出的参数化二元组合算子方法，将其推广为多元的情形．在成因分析的基础上，建立了大气污染物浓度预测的参数化组合算子模型，适应非线性问题．实例分析比较表明，该方法是有效的．     

PM2.5浓度预测模型的应用

空气中PM2.5浓度问题越来越受到各界的关注。根据PM2.5浓度数据的特征,首先选择ARIMA预测模型进行浓度预测;考虑到BP神经网络易陷入局部最小,而遗传算法具有全局搜索的能力,给出了遗传算法优化的BP神经网络预测模型;为了进一步提高预测精度,引入IOWGA算子,将ARIMA预测模型与遗传算法优化的BP神经网络预测模型相组合,给出了基于IOWGA算子的组合预测模型;最后经过实例仿真分析验证了模型的可行性和有效性,为PM2.5浓度预测提供基础资料。     

基于灰色组合预测的国内债券余额预测

针对加权几何平均组合预测是一种非线性的组合预测,提出了以对数灰色绝对关联度为指标的加权组合预测模型,将其形式线性化,针对该模型定义了组合预测模型的性质、优超预测方法及冗余度等概念,讨论了组合预测模型在满足一定的条件下可以是非劣性组合也可以优性组合预测,并给出一个判断冗余预测的简单方法的定理.并用此方法对国内债券余额进行预测,证明了该方法的有效性.     

基于算术平均贴近度的加权几何平均组合预测

引入和讨论了基于算术平均贴近度的加权几何平均组合预测模型及其性质.针对该模型定义了非劣性组合预测模型、优性组合预测模型以及组合预测冗余度的概念,讨论了在一定条件下,该组合预测模型存在非劣性及优性组合预测的条件,给出了判定冗余组合预测方法的判定定理.通过实例分析说明了基于算术平均贴近度的非线性组合预测模型的有效性.     

组合生态技术处理农村分散式污水净化规律

为解决农村分散式混合污水直接排放污染环境问题,以混有养殖废水的农村生活污水为研究对象,采用组合生态技术的办法,研究了该工艺下农村混合污水净化的影响规律,并采用BP神经网络预测模型对该处理系统的CODcr、BOD_5、氨氮的出口浓度进行预测并优化。结果表明:该组合生态技术能很好地处理农村混合污水,系统出水口的BOD_5、CODcr、氨氮等浓度达到排放标准且处理成本较低,符合农村污水处理的实际情况。采用遗传算法的BP神经网络优化模型能够较好地预测该系统的出水BOD_5、CODcr、氨氮浓度,将预测值与实验值对比求出相对误差,可对组合生态技术的处理效果进行评价,并求出最优温度、p H和流量条件下的优化处理效果。     

东北红豆杉愈伤组织培养研究

以东北红豆杉幼茎为培养材料诱导出愈伤组织，并分析了不同的激素组合、糖浓度、培养条件对愈伤组织诱导的影响。结果表明，NAA激素组合比2，4－D组合更有利于愈伤组织的诱导，在25℃、2％蔗糖、0．7％琼脂、每天光照12h条件下愈伤组织诱导率达100％。     

盐分浓度和钠浓度对蒙脱土保水性的影响

为了预测使用干燥地、半干燥地的再利用水灌溉给土壤构造带来的影响，调查了盐分浓度和钠吸附比（SAR）给蒙脱土的保水性带来的影响．用电导率（EC）表示盐分浓度，使用了NaCl12，20，50mol·m^-3和SAR5，10，20组合的溶液进行试验．当NaCl2mol·m^-3时由于EC低，所以全部的SAR显示高的保水性．因为EC变高，当NaCl20mol m^-3时SAR5跟SAR10相比保水性大幅度降低．在凝集条件下，保水性与SAR同时增加，在分散条件下没发现保水性的变化．在凝集状态下EC越高或SAR越低的时候，保水性降低．可以认为蒙脱土显示低保水性的时候会变成凝集构造．要控制蒙脱土的物理性质，盐分浓度和SAR的组合是很重要．     

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.     

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     

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

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