纸机干燥部纸幅水分控制系统优化方案的分析

为克服纸机干燥部烘缸传热过程中的大惯性,稳定烘缸干燥曲线,设计了以干空气进风量控 制作为主回路、以烘缸蒸汽压控制作为副回路,并引入前馈控制的阀位控制系统。探讨了采用排风 循环风量稳定气罩进风湿度、排风机排风量稳定零位及排风露点限制新的控制方案。结果表明：与 采用传统烘缸蒸汽压控制纸幅水分的控制系统相比,引入前馈控制的阀位控制系统,能快速稳定纸 幅水分;干扰对气罩排风露点的影响很小,排风露点设计值可取其最优化值;利用干空气进风量控 制的快速性和前馈控制的及时性,可使成纸水分波动很小,通过优化纸机质量控制系统中成纸干度 设定值可有效节约蒸汽与水资源的用量。     

热源塔结构特性对其换热性能影响的实验研究

利用搭建的开式热源塔实验平台进行实验,从塔身设置和进口参数两方面对热源塔换热性能进行分析。塔身设置包括喷嘴位置、进风口位置及有无填料层。进口参数包括室外空气温度、溶液进口温度及截面风速。实验结果证明热源塔下进风时的吸热效率优于上进风,其中无填料上喷下进风式换热性能最优;填料层可以促进气液之间的热质交换,但进风阻力变大,热源塔能耗比降低。对于进口运行参数,在下进风工况下,当风速增大时,热源塔的吸热效率均得到提升,但风速过大,吸热效率仅有微小提高,且塔身能耗比下降较快;溶液进口温度升高,热源塔的吸热效率提高幅度为30.1%~34.6%,进出口溶液温差降低了0.9~1.2℃;室外空气温度升高热源塔的进出口溶液温差明显增大,但吸热效率降低。     

热源塔结构特性对其换热性能的实验与分析

利用搭建的开式热源塔实验平台进行实验,从塔身设置和进口参数两方面对热源塔换热性能进行分析。塔身设置包括：喷嘴位置、进风口位置及有无填料层。进口参数包括：室外空气温度、溶液进口温度及截面风速。实验结果证明热源塔下进风时的吸热效率优于上进风,其中无填料上喷下进风式换热性能最优;填料层可以促进气液之间的热质交换,但进风阻力变大,热源塔能耗比降低。对于进口运行参数,在下进风工况下,当风速增大时,热源塔的吸热效率均得到提升,但风速过大,吸热效率仅有微小提高,且塔身能耗比下降较快;溶液进口温度升高,热源塔的吸热效率提高幅度在30.1%~34.6%之间,进出口溶液温差降低了0.9 ℃~1.2 ℃;室外空气温度升高热源塔的进出口溶液温差明显增大,但吸热效率降低。     

供冷工况地板送风静压层热力衰减的实验研究

对不同进风参数和不同室内热源条件下地板送风静压层的热力衰减进行了实验研究.实验结果表明:典型供冷工况下静压层内温度具有不均匀分布的特点,随着气流流程的增加,静压层内空气温升增大;随着送风量的减小,静压层内温度分布更不均匀;送风温度的改变对静压层内空气相对温升的影响较小;室内热源对静压层内热衰减影响较大;在楼板没有加绝热层的实验条件下,静压层的进送风温差与总进回风温差之比为18%～33%.     

立井井壁温度变化规律实测研究

为掌握生产期间主井、副井和风井井壁温度的变化规律,开展了实测研究。结果表明:进风井内井壁温度随风流温度的变化而变化,主井和副井的全年温度变化量分别为21℃、22℃,可近似表示为以年为周期的正弦函数;出风井井壁全年温度变化量约2℃,可近似忽略。分析认为:因井壁受热伸长受到围岩的约束而产生的竖直附加力是导致井壁破裂的原因之一。因此,进行井壁安全监测时,进风井必须监测温度变化,而出风井可不必监测温度变化。     

室内空气流动过程的模型实验研究

为了分析在不同的进风位置、射流方向以及进风温度条件下,房间壁温对室内空气流动的影响,在缩小模型实验的基础上,利用流动可视化和定量测量相结合的办法测量了不同工况下室内的空气流动形态、速度以及模型整体换热情况。结果表明:壁温恒定时,进风温度的降低引起水平进风方式的自由射流区缩短;垂直进风方式下射流形成的涡的中心位置向壁面靠近;中间垂直进风方式下射流向左侧偏转;右侧垂直进风方式下射流向右侧壁面偏转;同时浮升力引起的自然对流作用增强,换热温差加大,提高了围护结构漏热量。     

立体传质塔板帽罩空间浓度分布

立体传质塔板(CTST)罩体空间的浓度分布规律是板效率研究的基础.在φ600,mm的冷模实验塔内用富含CO2水-空气系统对CTST帽罩空间的气、液相浓度分布进行了测量.结果发现,罩内液相浓度沿帽罩高度方向总体呈降低趋势,同一高度上罩外液相浓度始终低于罩内液相浓度,气相浓度分布与液相浓度分布趋势相反;在帽罩的提升段,靠近喷射板的液相浓度明显高于中心位置的液相浓度,在喷射段,喷射板附近和帽罩中心的液相浓度则相差不大;正常操作条件下,提升段、喷射段和罩外传质量占总传质量的比率分别为50%～70%、10%～17%和20%～35%.考察了板孔气速和液体流量对罩体空间各区域传质量分配的影响.结果表明,随着板孔气速或液体流量的增大,提升段传质量比率减小,喷射段传质量比率增大.     

封闭式膜结构体育馆冬季热环境测试

在自然对流条件下,对封闭式膜结构体育馆的冬季室内热环境进行测试.根据不同的方位和高度共布置6个测点测量空气温度,同时得到了体育馆室内日照辐射强度、风速、黑球温度和相对湿度等热环境参数的变化曲线.分析了体育馆室内温度场的分布规律,采用修正后的预测投票平均值(aPMV)和预测不满意百分率(aPPD)指标对体育馆室内热环境进行评价.测试与分析表明:日照辐射是影响体育馆内部温度变化规律的主要因素.体育馆室内平均气温比外界高约3℃,随着室内高度的降低体育馆内升温时间逐渐延长,空气温度变化幅度呈现出显著的衰减性.测量时段内体育馆室内aPMV指标为-1.2~-0.5,热环境aPPD指标为15%~40%.在自然通风条件下,膜结构内无保温隔热设计的封闭式体育馆冬季室内热环境不满足舒适性要求.     

多炉芯气化炉轴向温度分布及影响因素

深入探讨了多炉芯气化炉成倍延长气化时间过程中集气空间内轴向温度分布,分析了集气空间轴向温度的主要影响因素;设计了煤气"引射"实验,详细研究了煤气排出速率对集气空间轴向温度分布,特别是集气罩内表面温度的影响,为煤气收集过程中集气罩的经济安装提供了技术基础。     

顶部多点竖向排烟下地铁隧道烟气控制研究

通过在某带有独立通风隧道的地铁区间隧道开展0.25～1.25 MW规模的现场火灾实验,对烟气温度分布进行分析,利用火灾动力学模拟工具(fire dynamics simulator, FDS)建立对应实际尺寸的数值模拟隧道模型,展开抑制下游烟气蔓延的通风隧道临界排风量以及排烟效率的研究。对于横向水平中心线温度,火源相对于排烟口的位置对火源附近温度升高区域的范围基本无影响。在地铁隧道内设置进风量可抑制烟气逆流,但同时会造成下游烟气失稳,排烟口无法完全排出高温烟气。对于在不同排风量及火源功率(heat release rate, HRR)的情况下,排烟效率先增大后保持不变;当排风量达到一定值,即等于临界排风量时,排烟口能够完全排出高温烟气,排烟口排烟效率为1,临界值与HRR相关。计算出临界Fr约2.7,略高于此前的研究。得到HRR的经验公式,排烟效率与无量纲HRR和无量纲风速的相关性呈现分段函数关系。     

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