绝热毛细管中制冷剂流动特性的一阶积分模型

制冷剂在绝热毛细管内的流动因存在汽液两相流而较为复杂．本通过引入两相流区压力和比容之间的一阶近似式,获得该问题的一阶近似积分解．在常见的制冷空调工况范围内,以制冷剂CFC-12、HFC-134a和HC-600a为工质,对该模型与分布参数模型进行了对比;同时也与实验数据进行了对比．结果表明：与分布参数模型的平均偏差小于1％,与实验数据亦较好吻合;计算速度较分布参数模型提高了一个数量级以上。     

空气源热泵毛细管节流空调系统的研究

根据气液两相流动的均相流假设,建立了绝热毛细管的分布参数模型.在冷热工况下空调系统制冷剂充注量差值的基础上,采用该模型模拟计算了应用毛细管节流的热泵型空调系统中主副毛细管的长度.将储液器法和采用主副毛细管控制制冷剂流量这两种方法进行了对比分析,结果表明,在控制系统高低压差和制冷剂流量时,两种方法各有利弊.因此,提出了采用主副毛细管和增加储液器相结合的方法控制热泵型空调系统冷热工况下的制冷剂流量.     

考虑壅塞特性的电子膨胀阀流量特性模型

分析了电子膨胀阀内部制冷剂的壅塞流动特性，应用均相流和冷冻流模型描述电子膨胀阀的流量特性，用亚稳态特性系数建立膨胀阀质量流量计算模型，并采用某型号电子膨胀阀的实验数据与所建模型的计算值进行对比.结果表明，该模型的计算值与实测值的偏差在-8.59%~7.56%以内.     

绝热毛细管内制冷剂流动的非平衡性

建立了制冷剂在绝热毛细管内流动的两流体模型,模型中考虑了气液两相间的速度滑移和温度滑移.采用6种制冷剂的流量实验数据验证该模型,结果表明,90%的预测值与实验值偏差在±10%以内,并且能合理预测压力的沿程分布.应用该模型研究了制冷剂在绝热毛细管内自蒸发过程的非平衡特性.结果显示:气液两相间的速度滑移和温度滑移在整个两相区一直存在,但在绝大部分区域内,这种非平衡性并不显著;与不考虑非平衡性的平衡均相流模型相比,本文模型计算的毛细管流量平均偏高7.3%.     

基于分布参数模型的满液式蒸发器性能模拟

基于流动沸腾换热的Chen氏加和模型，建立了满液式蒸发器分布参数的热力计算模型．采用分相流动模型计算制冷剂横掠管束的两相压降，考虑了压降对制冷剂饱和温度的影响；对于流程上下布置的满液式蒸发器，模型计算了制冷剂流量沿轴向的分布，改进了前人忽略制冷剂流量轴向分布对蒸发器性能的影响．应用该模型对一水平布置、2流程、采用强化管的满液式蒸发器进行了性能计算，热负荷的计算值与试验值吻合良好．同时，研究了不同管型、不同流程布置对满液式蒸发器性能的影响．     

微重力条件下气／液两相流压降实验研究

利用俄罗斯IL-76失重飞机对微重力条件下方形截面管道内的水/气两相流压降进行了实验研究．利用本次微重力气／液两相流压降实验结果对一些目前常用的基于地面常重力实验结果的两相流压降预测模型(均相模型、Lockhart-Martinelli—Chisholm模型和Friedel模型)在微重力条件下的适用性进行了评估．比较发现,均相模型和Lockhart-Martinelli—Chisholm模型预测结果和实验数据差异很大;而Friedel模型的预测结果尽管也与实验数据有着明显的差别,但在这些模型中是误差最小的．因此,可以利用Friedel模型来对微重力气／液两相流压降进行初步预估,而新的、更精确的模型将依赖于更有物理意义的分析方法及不同重力条件下气／液两相流压降实验的结果．     

R410a制冷剂性能参数的显式快速计算模型Ⅰ. 饱和线方程

在Martin-Hou方程的基础上,提出了R410a制冷剂在饱和线的热力学性能参数和传输特性参数的显式快速计算模型.该模型不存在迭代,在保证较高计算精度的同时,可以保证模型的计算速度和稳定性.以热力学性能参数计算软件REFPROP 7的数据源作为原始数据,在饱和线（139.00~343.32 K）范围内,对R410a制冷剂的性能参数进行拟合,并将该模型的计算结果与REFPROP 7数据源进行对比.结果表明：所有快速计算模型的总平均误差均小于1.174%,最大误差小于13.218%;其计算速度比REFPROP 7提高了2~4个数量级.     

水平圆管内油气两相流分层流向段塞流转变机理的实验研究

根据气液两相流一维波模型建立分层流向段塞流转变的判别准则,对水平管内气液两相流出现段塞流时的各相临界表观速度进行了理论预测,并对流型转变进行了分析.理论计算中,主要考虑了两相流体和管壁之间的摩擦和气液相界面之间的摩擦对流型转变的影响,并结合分层流理想化模型分析了发生流型转变时的临界参数.在内径分别为40 mm和50 mm的水平管道油气两相流实验系统中进行了流型转变实验,所获实验数据处理结果与理论计算结果进行了对比.对影响流型的管径、流速等因素的分析结果表明,该模型较好地预测管内分层流向段塞流的转变.     

水平分层/雾化流中相间滑移特性的理论研究

通过对水平分层／雾化流中液滴和其携带流体间交互作用的分析，提出了一个预测水平分层／雾化流中轴向液滴速度分布以及弥散相和连续相之间相对滑移的理论模型，通过计算获得了两相速度参数及相对滑移参数。计算与实验结果表明：无论是从液滴轴向速度分布变化趋势的定性分析，还是从与实验数据的定量比较来看，建立的模型都是合理的。液滴速度与气相速度分布不同，在垂直方向上液滴的轴向速度近乎呈线性分布。油／气两相流动时气核中液滴与气相的平均滑移比约为0．7。     

单回路不同布置形式的风冷冷凝器的模拟计算与分析

对3种单回路风冷冷凝器采用分布参数稳态模型进行了模拟计算，着重研究了不同的回路布置形式对换热性能的影响．计算结果表明，冷凝器在迎面风速相同时具有较小的制冷剂流量，以及在制冷剂流量相同时具有较大的迎面风速这两种情况下，由于换热比较充分，不同的回路布置形式对换热量有较大的影响；在换热不充分时，采用不同的回路布置形式换热量差异并不大；在其他情况相同时，采用逆流布置的换热量约比顺流布置高3％～4％．计算结果与前人的实验研究结果较为一致，说明采用该计算模型便于比较多种不同的回路布置形式对冷凝器性能的影响．该计算模型可用于冷凝器回路的优化设计．     

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     

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