黄原胶水溶液管道流动减阻特性的试验

对连续循环光滑管道(直径分别为5,10,20 mm)中黄原胶水溶液流动的减阻特性进行了试验,分析了黄原胶减阻的浓度效应、管径效应以及抗剪切特性,得到了减阻率与黄原胶水溶液浓度的关系曲线、雷诺数(Re)与减阻率的影响曲线以及减阻率与剪切时间的变化曲线.结果表明:黄原胶是很好的减阻剂,在较低Re流动时黄原胶在相对较小直径(5,10 mm)管道中表现为B型减阻特性,而在较大管径(20 mm)中则为A型减阻;在高Re时黄原胶水溶液在3种管径管道流动中皆表现为B型减阻,由于其主要具有B型减阻特性,使得黄原胶具有较好的抗剪切特性.     

阳离子型表面活性剂与非离子型聚合物相互作用减阻研究

为探究表面活性剂与聚合物相互作用的减阻效果,对阳离子型表面活性剂CTAC和非离子型聚合物PAM的纯溶液和混合溶液进行湍流减阻实验测量。结果表明:表面活性剂CTAC溶液中加入不同浓度非离子型PAM,混合溶液减阻的临界温度均相同但低于相应纯CTAC溶液的临界温度,而超过临界温度后混合溶液减阻能力的下降趋势更缓;各个温度下混合溶液的减阻稳定区和纯CTAC溶液基本一致,且减阻稳定区内的摩擦系数也都相同;在超过临界雷诺数的减阻破坏区,混合溶液减阻效果更好,且PAM浓度升高,溶液减阻能力增强。提出了表面活性剂胶束联结在聚合物长链上形成了内部交联密集、结构稳定的混合网状结构模型,应用此模型合理解释了CTAC溶液中加入非离子型PAM形成的混合溶液的湍流减阻现象。     

桥梁断面三分力系数的雷诺数效应

在TJ- 2风洞中 ,测量了近 2个数量级的雷诺数范围内不同宽高比的 2类桥梁断面的三分力 ;研究了桥梁断面三分力系数雷诺数效应、宽高比对断面三分力系数雷诺数效应的影响 .近流线型桥梁断面的阻力系数、升力系数都有明显的雷诺数效应 ;Π型断面阻力系数雷诺数效应与近流线型断面规律相反 ,升力矩及升力系数雷诺数效应不明显 ;宽高比对三分力系数雷诺数效应有明显的影响 ;紊流可以作为抑制阻力系数雷诺数效应的有效措施     

模型血泵相似性设计及验证

以日本磁悬浮离心式血泵为原型,设计制作了放大2倍的模型泵,用不同流体对泵的相似性进行实验验证发现,模型泵和原型泵具有很好的相似性;采用黄原胶溶液模拟血液流体比水的相似性更好,质量分数为0.06%和0.04%的溶液比其他浓度溶液更接近血液流体.在溶液浓度较低时,溶液的非牛顿特性对离心泵的相似设计影响较小,模型泵实测相似临界雷诺数和转速分别与相似设计的临界雷诺数和转速一致;在溶液浓度较高时,溶液的非牛顿特性对离心泵的相似设计影响较大,模型泵实测相似临界雷诺数和转速远小于相似设计的临界雷诺数和转速.     

矩形微细通道内流场的可视化实验研究

以蒸馏水为工质,水溶伊红为着色剂,对水力直径为419.2μm,相对粗糙度为3.86%的矩形不锈钢微槽内流动流态进行了可视化实验研究.经光学显微镜放大后由CCD相机拍摄,得到了不同Re数下矩形微槽内的流型图,同时测量了微槽内的摩擦阻力系数.可视化实验表明随Re数增大,出口段、中间段及入口段依次出现层流向湍流过渡,层流向湍流过渡是渐进的、连续的.摩擦阻力实验表明无论层流区还是过渡区,摩擦阻力系数均高于传统理论预测值,由于转捩提前层流区摩擦阻力系数随Re数增大,与传统理论预测值偏差越大.可视化实验与摩擦阻力实验均表明层流向湍流过渡的临界Re数在1 500左右.     

黄原胶水溶液的流变性能

采用ARES流变仪研究了质量浓度为1.0～40.0 g/L的黄原胶水溶液在303.15～343.15 K的流变性能.结果表明:黄原胶水溶液为假塑性流体,幂律模型能很好地关联其流变方程;当质量浓度为2.0 g/L时,黏度和温度关系满足Arrhenius定律,随着黄原胶质量浓度增大,温度对黏度的影响不再符合Arrheniu...     

基于刚性节段模型风洞试验的输电导线阻力系数研究

为了研究多分裂导线静力风荷载,进行了原尺寸刚性节段模型测力风洞试验,计算得到了多种直径导线阻力系数,并分析了包括雷诺数效应、屏蔽效应等因素对其结果的影响.研究结果表明,导线阻力系数试验结果较规范取值小,且由于导线表面粗糙度及紊流度的增加,会使其临界区雷诺数范围提前,尽管导线雷诺数处于名义的亚临界区域,其阻力系数依然随雷诺数变化比较敏感.对于多分裂导线而言,由于上游导线的遮挡干扰,导线整体阻力系数有所降低,必须考虑这种屏蔽效应的影响.拟合得到了考虑雷诺数效应以及屏蔽效应在内的输电导线阻力系数经验公式,为输电导线静力风荷载的计算提供一定的参考.     

硼交联N_2伴注泡沫压裂液的阻力特性研究

液氮泡沫伴注压裂液的阻力性能对于有效实施压裂工艺、选择合理的压裂参数、进行更为准确的裂缝预测、评估压裂效果都至关重要.利用高参数泡沫压裂液实验回路详细研究了模拟实际压裂条件下N2泡沫压裂液的阻力特性.研究表明:N2泡沫压裂液的摩擦压降梯度随着流速的增大而增大,随着温度的升高而减小,随着压力的增大而增大;摩擦阻力系数随着流速增大而增大,随着温度的升高而减小,而其随着压力的变化特别复杂.通过实验研究得出了N2泡沫压裂液在15~45MPa范围内摩擦阻力系数和广义雷诺数之间的计算关联式,其在本文实验工况下的平均计算误差为10.2%.     

粗糙度对微细通道内流动特性影响的实验研究

对几何特性相似而粗糙度不同的3种不锈钢矩形微槽内水、乙醇和正己烷的流动特性进行了实验研究.研究发现,在层流区随着雷诺数(Re)的增大,摩擦阻力常数fRe也缓慢增大,与传统理论的fRe是常数不同,且相对粗糙度越大,fRe值也越大.对于相对粗糙度较小(k/D_h<3%)的两种微槽转捩Re均在1 685～1 760之间,与传统理论相比,转捩并未提前.但相对粗糙度为3.15%的微槽的转捩Re数为1 500,与传统理论相比,转捩已提前.层流区摩擦阻力系数均高于传统理论预测值,相对粗糙度较小(k/D_h<3%)的两个微槽的摩擦阻力系数在Re<1 600的层流区域基本相同。但在Re=200～2 800的测量范围内,相对粗糙度大于3%的微槽的摩擦阻力系数均比相对粗糙度小于3%的微槽的要大.过渡区域的摩擦阻力系数均比传统预测值高30%～40%.工质极性对摩擦阻力的影响很小.     

无粘土冲洗液的降泵压性能研究

本文讨论了田菁减阻液的试验研究结果,即雷诺数、浓度、管径、机械降解及阳离子等因素对田菁减阻性能的影响。还探讨了紊流减阻的机理及介绍了田菁减阻液在岩心钻探中的初步应用效果.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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