定容燃烧弹中预混均匀充量的层流燃烧过程模型

在分析定容燃烧弹中预混均匀充量层流燃烧过程的基础上，建立了该燃烧过程的计算模型，并且编制了计算程序软件，以甲烷－空气在定容燃烧弹中的预混层流燃烧为例，用计算的方法，研究了初始压力、温度、空燃比以及不同的火花塞位置等因素的变化对燃烧过程的影响，得到了一些有益的结论。     

低热值气体燃料层流燃烧特性

在定容燃烧弹中开展了当量比、燃料组分、初始压力对低热值气体燃料层流燃烧特性影响的试验研究,建立了准维双区模型,基于在定容弹内实测的压力曲线,计算了规范化质量燃烧率.研究结果表明:燃料中氮气比例的增加导致压力峰值降低,火焰发展期和燃烧持续期增长;化学计量比附近的燃料燃烧进行的较充分,压力峰值最高,火焰传播速率最快,燃烧持续时间短;初始压力的增加使质量燃烧率下降,燃烧持续期有所延长.     

电极几何参数对离子电流影响的试验研究

在定容燃烧弹中进行了正负电极面积对天然气-空气混合气燃烧产生的离子电流影响的研究,并将高速摄影仪在燃烧过程中拍摄的纹影照片与相应的离子电流进行分析对比.结果表明:电极直径和所布置的圆盘面积等参数不影响离子电流曲线的形态,曲线均存在点火、前锋区、后焰区3个阶段,可以完整地体现燃烧信息;电极几何参数影响电流的幅值,而且正电极面积的影响大于负电极.     

基于定容燃烧弹的正丁醚压力振荡特性试验研究

基于定容燃烧弹实验平台,在环境压力为0.05～0.20 MPa、温度为423～453 K、当量比为0.7～1.6条件下开展正丁醚的压力振荡特性试验研究,获得正丁醚燃烧过程中的燃烧压力、火焰形态、燃烧弹振动、声压实验数据并对其进行分析。研究结果表明：正丁醚在较低温度、较高压力下,当量比为1.5左右时产生的压力振荡强度最大,燃烧过程中的压力、振动、声压、亮度等信号具有相同的变化规律,均呈现出随温度增加缓慢降低、随压力增加显著增强、随当量比增加先增后减的趋势。随着压力振荡强度增大,振荡的主频向高频方向移动。正丁醚的火焰不稳定性与压力振荡的产生存在一定关系。     

电极位置与电极面积对离子电流影响的试验研究

在定容燃烧弹中将5个不同面积的电极安装在容弹中的不同位置,通过采用不同测量电极组合测量了燃烧过程中产生的离子电流信号。以离子电流信号、燃烧压力信号和火焰纹影照片为基础数据,分析了电极位置和电极面积对离子电流的影响。试验结果表明:电极位置会影响离子电流的出现时刻、大小、峰值及峰值时刻等特征参数;当正电极一定时,离子电流升高的次数随负电极数量的增加而增多,说明离子电流能够反映电极附近的局部燃烧信息;火焰与正电极、负电极可接触面积影响着电极吸收的电荷量及离子电流的幅值,且负电极面积的影响大于正电极面积的影响。该研究结果可为离子电流法获取发动机缸内燃烧信息的应用提供理论依据。     

乙醚在亚/超临界环境下喷雾燃烧及其产物

为了探究亚/超临界环境下燃料在定容燃烧弹内的燃烧过程及其产物,采用高压共轨燃料喷射系统试验台和单次喷射仪进行燃料供给。通过高速相机和阴影仪进行图像数据的采集,利用烟气分析仪进行燃烧产物的收集测量。试验结果表明:乙醚的燃烧火焰呈现较明亮的球状。在临界压力点时,喷雾燃烧贯穿距最短,火焰面积最小。乙醚喷雾燃烧后,一氧化碳(CO)的生成量随环境压力的升高而连续下降,碳氢化合物(HC)的生成量则在临界压力处出现突变。燃烧火焰特性和产物生成规律所呈现的差异性,主要是由于亚/超临界环境下燃料的物性参数和破碎蒸发机理的不同。     

定容燃烧弹中预混流燃烧的数值模拟

发展了一种新型预混湍流燃烧的数值模型。该模型基于准维模型的基本思想,摒弃了湍流燃烧速度模型,以数值生成的湍流场对火焰前锋面的客观影响推动燃烧计算过程,消除了人为经验作用。利用模拟得到的湍流速度场,实现了对火焰几何形状的二维模拟,利用该模型,计算和讨论了当量燃空比分别为０．９和０．７时,定容燃烧弹中预混湍流燃烧的特点,以及湍流强度和湍流标尺对燃烧的影响。     

太原城区空气颗粒物中多环芳烃的碳同位素组成研究

报道了太原城区空气颗粒物中多环芳烃(PAHs)化合物的稳定碳同位素组成特征,并讨论了多环芳烃的来源.气相色谱/燃烧系统/同位素质谱(GC/C/IRMS)分析表明,PAHs的δ13C值在非采暖季为-25.1‰～-27.2‰,采暖季为-23.8‰～-28.6‰.统计表明,不同采样点的样品中PAHs的δ13C区别不明显 (0.2‰＜σ＜ 0.9‰).两个季节四环多芳香烃化合物荧蒽、芘和苯并(a)蒽的δ13C没有明显的区别,δ13C的范围为-23.8‰～-25.9‰.随着分子量的增大其化合物的碳同位素组成富集13C 的能力减小,非采暖季的苯并(a)芘、茚并(1,2,3-cd)芘和苯并(ghi)苝的δ13C值分别为-27.2‰、-26.5‰和-25.4‰,采暖季为-26.1‰、-28.6‰和-24.1‰.利用二元复合同位素模型,估算了机动车尾气和煤的燃烧对太原城区苯并(a)芘、茚并(1,2,3-cd)芘和苯并(ghi)苝的贡献,机动车尾气排放对苯并(a)芘、茚并(1,2,3-cd)芘和苯并(ghi)苝的贡献率分别为50%、44%和35%;煤的燃烧产生的烟尘对其贡献为50%、56%和65%,太原市城区五环和六环多环芳烃污染是机动车排放和煤的燃烧为主的复合性污染.     

一种多点点火的多功能定容燃烧实验装置

文章设计了一种能多点点火的多功能定容燃烧实验装置,可用于预混层流燃烧、壁面多点点火和燃料喷雾特性等实验研究;介绍了该定容燃烧实验装置的整体结构,并分别介绍了配气系统、数据采集系统、加热系统、点火系统和高速纹影系统等子系统;重点说明了该定容燃烧实验装置多点点火系统的组成及实施方法;最后进行了常温、常压条件下不同当量比甲烷...     

定容燃烧弹中预混湍流燃烧的数值模拟

发展了一种新型预混湍流燃烧的数值模型．该模型基于准维模型的基本思想,摒弃了湍流燃烧速度模型,以数值生成的湍流场对火焰前锋面的客观影响推动燃烧计算过程,消除了人为经验的作用．利用模拟得到的湍流速度场,实现了对火焰几何形状的二维模拟．利用该模型,计算和讨论了当量燃空比分别为０．９和０．７时,定容燃烧弹中预混湍流燃烧的特点,以及湍流强度和湍流标尺对燃烧的影响．模型的模拟结果和实验结果有很好的吻合性,这说明模型是合理的．     

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     

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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