三氟乙烷的气相音速测量与热力学性质研究

采用球型腔体声学共振法测量了新型制冷剂三氟乙烷(HFC143a)的气相音速,得到了压力在200～800kPa范围内,温度分别为293.61、302.96、313.19和323.18K时的4条等温线共28个音速数据.根据实验数据,由热力学关系式得到了HFC143a的理想气体比定压热容和第二音速维里系数等热力学性质,同时根据现有的高精度实验数据拟合了HFC143a的理想气体比热方程.温度、压力和气体音速测量的不确定度分别为±14mK、2.0kPa和±0.0037%.     

293～347 K温度区间二甲醚饱和蒸气压的实验研究

为了给二甲醚作为替代燃料和制冷剂的研究提供基本物性数据 ,对 2 93 7762～ 3 47 464 3K温度区间的二甲醚饱和蒸气压进行了测量 ,其中实验结果的温度不确定度小于± 2mK ,压力不确定度小于± 0 7kPa .同时 ,利用获得的实验数据拟合了一个新的Wagner型二甲醚饱和蒸气压方程 ,新方程与实验结果的平均偏差为 0 0 2 3 % ,最大偏差为 0 0 96% ,适用温度范围为 2 93～ 40 0K .     

高精度流体热物性测试实验系统的研制

在分析各种流体热物性参数测量要求的基础上,借鉴前人研究经验,结合最新的温度、压力等参数测量与控制技术,完成了流体热物性测试用的温度测量系统、高精度控温油/水槽、高精度控温酒精槽、压力测量系统、真空及配气系统、配套的测试与控制软件等的研制与开发,最终形成了一套相对完整的测试实验系统平台.在实验系统的运行范围内,最佳的温度测量不确定度小于±1mK,恒温槽15min的温度波动度可优于±1mK,压力测量的准确度为量程的0 01%.大量的实际运行结果表明:新研制的流体热物性测试实验系统性能稳定,测试结果可靠,为目前正在进行的流体热物性测试自动化研究奠定了良好的基础.     

HFC152a/HCFC22混合工质气相粘度实验测量

利用振动盘式粘度计对混合工质的气相粘度进行了实验测量.实验采用相对测量的方法,测量了真空下的对数衰减率;通过氮气的粘度测量获得了工作方程的修正项,并通过测量HCFC22的粘度对实验系统的准确性和可靠性进行了检验;然后对HFC152a/HCFC22(质量分数15%/25%)的气相粘度进行了测量,测量温度293～370 K,压力0.1～1.9 MPa,实验测量的不确定度为3%,并关联了粘度、温度和密度的经验公式.     

高压振动弦黏度计实验系统的研制

为了获得准确的流体黏度数据,基于振动弦理论,研制了一套高压振动弦黏度测量实验系统.该系统具有精度高、稳定可靠、测量范围大等特点,测量温度范围为243～400K,压力范围为0～40MPa.利用标准物质甲苯对实验系统进行了标定和检验,黏度测量的不确定度为±2.0%.此外,利用制冷剂R134a对实验系统进行了检验,并将实验结果与文献值进行了比较.结果表明,实验系统准确可靠,可以用于流体黏度的高精度测量.     

二氟乙烷气体音速与理想气体比热容实验研究

用球共鸣声学法测量了工质二氟乙烷(HFC152a)在温度分别为293.86、302.96、313.19和323.16 K时,压力为200～420 kPa的四条等温线共24个音速数据.根据实验数据,由热力学关系式得到了HFC152a在四个温度下的理想气体比热容和第二音速维里系数.同时根据现有的高精度实验数据拟合HFC152a的理想气体比热容方程.这些研究为HFC152a在工程上的应用提供了必需的热物理性质基础数据.     

基于磁悬浮密度计的高精度流体PVT测量系统

建立了一套基于磁悬浮密度计的流体PVT测量系统,其温度测量范围203.15~423.15 K,标准不确定度为0.005 K,压力测量范围0~7 MPa,标准不确定度为700 Pa.通过对恒温系统的改进,缩短了实验本体达到热平衡的时间,提高了温度稳定性.利用该系统对高纯氮气在271~345 K,0~6 MPa范围内进行了密度测量,实验结果与NIST REFPROP9.0数据相比偏差在0.1%以内,并对由于拟合维里方程的不确定度、温度测量和压力测量不确定度引起的密度结果的不确定进行了分析.     

1,1,1,2,3,3,3-七氟丙烷的热力性质

为获得不破坏臭氧层的环保工质的热物性数据 ,对HFC- 2 2 7ea的热力学性质进行了研究 ,精确测量了 2 43～375 K的饱和蒸气压 ,使用膨胀 -定容法测量了 2 78～ 377K,压力 0 .2 6～ 2 .6 MPa的 HFC- 2 2 7ea的气相 p VT性质 ,温度和压力测量的最大不确定度分别为± 10 m K和± 5 0 0 Pa。使用测量结果关联了 HFC- 2 2 7ea的蒸气压方程 ,导出了维里系数、饱和气相密度、饱和蒸发焓 ,并关联了截断维里型的状态方程用于再现 HFC- 2 2 7ea气相区的热力性质。     

高精度溶解度实验系统的研制与验证

研制了一套高精度制冷工质溶解度实验系统,由自行开发的测控软件进行计算机实时测控.实验系统包括高精度温度测量系统(在253.15~363.15 K范围内,测量的不确定度小于±14mK),高精度压力测量系统(在0~3.5 MPa范围内,测量的不确定度小于±1.6 kPa),高精度恒温水浴(293.15~363.15 K),高精度恒温酒精浴(253.15~293.15 K),真空及配气系统等.对283.15~348.15 K温度范围内HFC-134a的饱和蒸气压进行了测量,并与标准值进行了比较,测量的平均偏差为0.54%.用此装置对制冷剂R22在吸收剂N,N-二甲基甲酰胺中的溶解度进行了实验研究,并同文献提供的数据进行对比,结果表明该实验系统具有较高的精度.     

多相流体流量测量的采样分流方法

借用数据采集中的采样概念,提出了一种多相流采样分流方法,以获得具有高度代表性的分流体,从而提高多相流体的流量测量精度.首先,以足够高的频率从被测多相流中采集流量数据(分流体),然后把采集到的分流体分离成单相流体,再分别用单相流量计测量其流量,最后根据采样关系确定被测多相流体的总流量.由于分流体只占总流量的很少一部分,因此所需分离器的体积可以大幅度缩小,基本接近普通单相流量计的大小.在油气水三相流实验回路上进行了实验研究,结果表明在实验范围内,采样机构运转平稳、可靠,获得的分流体具有足够高的代表性,测量结果与流型无关,干度偏差小于2%,总流量的测量不确定度小于3.82%.     

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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