4类碳氢燃料的高温燃烧反应简化建模

以正辛烷(n-C₈H₁₈)、异辛烷(i-C₈H₁₈)、甲基环己烷(CH₃cyC₆)和正丁基苯(A1C₄H₉)4类大分子碳氢燃料为对象,探究了简化建模方法对含不同官能团的碳氢化合物燃烧反应动力学的适用性。建立了上述4类碳氢燃料的简化反应动力学模型,包含124个化学组分和854个基元反应;采用热解反应和氧化反应过程的主要中间产物分布、点火延时时间、层流燃烧速率等基础燃烧数据对该模型进行验证;分析了4类燃料中间产物的碳分布及对宏观燃烧特性的影响;以n-C₈H₁₈为例,采用误差传播直接关系图谱法对所建简化模型进行进一步简化,简化后的模型包含56个化学组分和387个基元反应。结果表明:本简化建模方法不仅对直链烷烃和支链烷烃有较好描述,同时适用于环烷烃和烷基芳香烃的燃烧化学;不同官能团的大分子碳氢燃料裂解中间产物的不同决定了其宏观燃烧特性;该建模方法通过进一步简化,可有效与先进计算...     

隐式溶剂下丙氨酸体系电荷分解分析的理论计算

采用密度泛函理论中的B3LYP方法优化隐式溶剂下丙氨酸(Ala)分子的几何构型, 并用同法计算隐式水(H₂O)及甲醇溶剂下Ala体系片段的轨道波函数及电荷分解分析(CDA). 结果表明, 在隐式溶剂甲醇和H₂O下, CH₃片段的扩展电荷分解分析(ECDA)计算结果相差0.001 3; NH₂片段的ECDA计算结果相差0.000 8, 定量结果基本一致, CH₃和NH₂片段的CDA计算结果r_i对二者的定性结果基本一致.     

原位光反应法合成过氧桥连草酸铀酰配合物

在室温和实验室灯光照射条件下,通过原位光化学反应,分别以乙二胺和二亚乙基三胺为模板,合成3种过氧桥连的草酸铀酰配合物[NH₃(CH₂)₂NH₃]₃[(UO₂)₂O₂(C₂O₄)₄]·4H₂O (1),[NH₃(CH₂)₂NH₂(CH₂)₂NH₃]₂[(UO₂)₂O₂(C₂O₄)₄]·2H₂O(2)和[NH₃(CH₂)₂NH₂     

高负载铜基SSZ-13分子筛催化剂SCR模型研究

随着日益严格的排放法规出台，降低重型柴油机的氮氧化物(NO_x)排放已成为研究的重点．为提高SSZ-13分子筛催化剂在低温下的二氧化氮(NO₂)转化效率，通过数值仿真的方法研究了高负载铜基的小孔径分子筛催化剂在不同工况下的最佳NO₂占比情况．利用GT-SUITE软件建立了一维反应器模型以及催化反应动力学模型，采用数值模拟计算的方法对选择催化还原(selective catalytic reduction,SCR)系统内化学反应进行了研究．模型考虑了423～673 K的温度范围内，氨气(NH₃)的吸附、脱附和氧化反应、一氧化氮(NO)氧化反应、NO_x的还原反应以及硝酸铵(NH₄NO₃)的分解反应，并且在排出气体中监测重要的温室气体——氧化亚氮(N₂O)的排放量．结果表明：在高负载铜基的SSZ-13分子筛催化剂作用下，NO₂与NH₃反应生成的NH₄NO<...     

单头部模型燃烧室滑动弧等离子体点火数值仿真研究

针对航空发动机燃烧室内滑动弧等离子体点火的特性,采用数值模拟的方法对航空发动机单头部模型燃烧室进行滑动弧等离子体点火研究,将滑动弧等离子体简化为动态热源,并将滑动弧等离子体点火与电火花点火对比,归纳2种点火方式下燃烧室点火过程中温度分布与火焰演化的规律,总结滑动弧等离子体点火的特性。计算结果表明,电火花点火和滑动弧等离子体点火2种点火方式所能达到的平均温度峰值基本相同。在滑动弧等离子体点火过程中,放电功率为200 W、空气流量为25 m3/h条件下,余气系数为1时,着火延迟时间为224.6 ms;余气系数为2时,着火延迟时间为324.9 ms;余气系数为4时,着火延迟时间为878.7 ms。另外,在放电功率为200 W、余气系数为1的条件下,当空气流量为15 m3/h时,着火延迟时间为194.8 ms;空气流量为35 m3/h时,着火延迟时间为298.9 ms。结果表明着火延迟时间随着余气系数、空气流量的增大而增长。     

老化态Pd/Rh基三元催化器的起燃及次生污染物生成特性研究

为探究天然气发动机三元催化器(three-way catalytic converter, TWC)长期使用后起燃特性及次生污染物生成特性的变化规律，文章建立当量比燃烧的天然气发动机Pd/Rh基催化器的表面反应机理模型，利用试验数据验证模型的准确性，研究贵金属分散度对CH₄、CO、NO排放物起燃特性以及次生污染物NH₃、N₂O生成规律的影响。结果表明：相较于新鲜催化器，老化催化器虽然仍能实现对气体排放物的有效转化，但是随着贵金属分散度的降低，CH₄、CO、NO的起燃温度明显增加，起燃特性变差；贵金属分散度还会影响次生污染物的生成规律，分散度增加时，催化剂表面对污染物气体的吸附能力增强，增加了次生污染物的消耗，次生污染物的生成有所减少。     

高频交流电场对预混稀燃火焰影响的机理分析

为了明确高频交流电场对火焰燃烧的影响机理,分别选取了初始压力为0.1、0.3、0.5 MPa的CH₄/空气和初始压力为0.1MPa的CH₄/O₂/Ar预混稀燃气,通过在定容燃烧弹内的网状电极上加载幅值为5kV、频率为15kHz的高频交流电场,对比分析了在高频交流电场下两种预混气火焰传播特性的异同,以及不同初始压力下CH₄/空气火焰传播特性的异同。结果表明:加载高频交流电场后,随着初始压力的增大,电场对CH₄/空气火焰面发展的影响程度逐渐减小,平均火焰传播速度增大率逐渐减小;随着过量空气系数的增大,加载电场后对CH₄/空气火焰的拉伸作用逐渐减小,对CH₄/O₂/Ar火焰的拉伸作用逐渐增大,CH₄/空气的平均火焰传播速度增大率逐渐减小,CH₄/O₂/Ar的平均火焰传播速度增大率逐渐增大,电场对两种混合气火焰传播的影响趋向相同。这说明在CH_4<...     

耦合详细化学动力学的HCCI发动机工作过程三维数值模拟

将详细化学动力学的HCCI单区模型嵌入三维流体力学程序中，取代传统内燃机三维数值模拟中简化燃烧模型，利用详细化学反应动力学计算三维燃烧过程，建立三维CFD耦合详细化学反应动力学模型.生成了带复杂进气道的实际燃烧系统的贴体计算网格，建立了缸内直喷HCCI燃烧系统进气-喷雾-混合气形成-压缩-燃烧工作过程的模型.为满足模拟整个HCCI发动机物理化学过程（包括进气，压缩，喷雾，燃烧和排放）执行时间的要求，提出了一套能使计算工作量大为减少的详细化学反应动力学与三维CFD耦合的模拟策略，利用试验方法确定计算边界条件，预测了进气-喷雾-燃烧-排放的HCCI发动机工作过程，通过发动机台架试验对比验证了模型的准确性.     

氨法脱硫中亚硫酸铵的氧化工艺参数

通过改变亚硫酸铵初始浓度、硫酸铵初始浓度、反应温度、混合液pH值、空气流量、催化剂浓度, 研究氨法脱硫中亚硫酸铵氧化率的变化. 结果表明: (NH₄)₂SO₃的浓度与 (NH₄)₂SO₃的氧化率成反比关系; 初始 (NH₄)₂SO₄浓度越大, (NH₄)₂SO₃氧化率越低; 当反应温度为40~60 ℃时, 随着温度的升高,  (NH₄)₂SO₃的氧化率不断增大;  (NH₄)₂SO₃氧化率受混合溶液pH值的影响, 较合适的pH值为5.5; 当空气流量为100~400 L/h时, 随着空气流量的增大,  (NH₄)₂SO₃的氧化率增大; 随着催化剂CoSO₄浓度升高,  (NH₄)₂SO₃氧化率增大.结合氨法脱硫工程实例考虑, 当反应温度控制在50 ℃ 左右, (NH₄)₂SO₃采用低浓度氧化, 混合液pH值为5.5, 空气流量为300 L/h, 催化剂浓度较高时, (NH₄)₂SO₃的氧化率较高.     

(NH4)2SO4-NH3-H2O体系浸出高碱性脉石低品位氧化铜矿

以高碱性脉石低品位氧化铜矿为研究对象,针对该矿样钙镁含量高的特点,采用氨水-硫酸铵浸出体系进行了常温常压浸出实验.针对该矿样的主要含铜矿物孔雀石(Cu₂(OH)₂CO₃),基于质量和电荷的双守恒的条件下构建的浸出体系中建立Cu₂(OH)₂CO₃-(NH₄)₂SO₄-NH₃-H₂O的热力学模型,采用Matlab的拟合功能与diff和solve函数算出不同硫酸铵浓度时氨浸出孔雀石的最佳氨浓度和总铜离子浓度.实验考察了浸出氨水浓度、氨铵比、液固比对铜浸出率的影响.实验结果表明,高碱性脉石氧化铜矿石适宜浸出条件为氨水浓度1.2mol/L,氨铵比2∶1,液固比3∶1,该条件下铜浸出率较高,达到约70%.实验结果与热力学计算结果基本吻合.     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has