低浓度冶炼烟气二氧化硫吸收解析研究

通过柠檬酸钠缓冲溶液对低浓度冶炼烟气SO2的吸收解析研究,发现影响吸收效果的因子很多,包括吸收液质量浓度和初始pH值、液气比、解析后二氧化硫体积分数等.研究表明适宜的柠檬酸吸收液浓度为0.5～1.25 mol/L,pH值为4.0～5.0,液气比以不大于1:400较为理想.     

汽油低温氧化特性及替代物模型研究

本文利用射流搅拌反应器对国产汽油以及汽油替代物模型中的重要组分异辛烷开展了低温氧化特性实验研究,并通过对国产实际汽油进行组分测量,获得了不同组分类型的摩尔分数.结合实际汽油的组分结构和物化特性,选取了五种代表性组分来构建合适的汽油替代物模型并发展了动力学机理,利用该机理分别对单组分燃料和实际汽油的低温氧化特性进行了模拟...     

榆树林油田低渗储层微观特征及剩余油分布

低渗透储层是目前国内外油气勘探的主要对象之一。勘探、开发实践证明,孔隙结构特征是影响低渗储层性质的关键因素。综合镜下普通薄片、铸体薄片观察、普通压汞、恒速压汞等多种资料研究了低渗储层的微观孔喉分布特征,并根据渗透率将孔隙结构类型分为三类,结合荧光薄片分析将水洗后微观剩余油分为七类,研究了微观剩余油与微观孔隙结构的关系,认为低渗透储层微观剩余油主要是粒间吸附状、孔表薄膜状和簇状,一类孔隙结构中剩余油的形成主要和碎裂泥化和卡断作用有关,三类孔隙结构中剩余油的形成主要和绕流作用有关。     

低渗透油田表面活性剂增注效果预测方法研究

针对低渗透油田在注水开发过程中注入压力高、压力传导慢等问题,室内进行了表面活性剂相对渗透率和天然岩心降低注入压力等实验研究。实验结果表明,在水驱基础上,天然岩心注入浓度为0.5%的NS—1表面活性剂后,后续水驱压力降低25%以上,降压效果明显。根据油水相对渗透率曲线,在油水两相径向稳定渗流条件下,对表面活性剂增注效果、段塞尺寸与增注量的关系等进行了预测。     

Mechanical properties of oriented low‐density polyethylene with an oriented lamellar‐stack morphology

A quantitative study was undertaken of the anisotropy of low‐strain mechanical behavior for specially oriented polyethylene with controlled crystalline and lamellar orientation. The samples were prepared by the die drawing of injection‐molded rods of polyethylene and annealing. This produced a parallel lamellar structure for which a simple, three‐dimensional composite laminate model could be used to calculate the expected anisotropy. Experimental data, including X‐ray strain measurements of the lateral crystalline elastic constants, showed good quantitative agreement with the model prediction. The X‐ray strain measurements confirmed that the amorphous regions exert large constraints on the crystalline phase in the lateral directions, where an order of magnitude difference was found between the measured apparent lateral crystalline compliances in the lamellar‐stack sample and the expected values for a perfect crystal. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 755–764, 2000     

A two‐scale low‐Reynolds number turbulence model

In this study, a two‐scale low‐Reynolds number turbulence model is proposed. The Kolmogorov turbulence time scale, based on fluid kinematic viscosity and the dissipation rate of turbulent kinetic energy (ν, ε), is adopted to address the viscous effects and the rapid increasing of dissipation rate in the near‐wall region. As a wall is approached, the turbulence time scale transits smoothly from a turbulent kinetic energy based (k, ε) scale to a (ν, ε) scale. The damping functions of the low‐Reynolds number models can thus be simplified and the near‐wall turbulence characteristics, such as the ε distribution, are correctly reproduced. The proposed two‐scale low‐Reynolds number turbulence model is first examined in detail by predicting a two‐dimensional channel flow, and then it is applied to predict a backward‐facing step flow. Numerical results are compared with the direct numerical simulation (DNS) budgets, experimental data and the model results of Chien, and Lam and Bremhorst respectively. It is proved that the proposed two‐scale model indeed improves the predictions of the turbulent flows considered. Copyright © 2000 John Wiley & Sons, Ltd.     

A novel gas sensor from polymer‐grafted carbon black: responsiveness of electric resistance of conducting composite from LDPE and PE‐b‐PEO‐grafted carbon black in various vapors

The composite of low‐density polyethylene (LDPE) filled with carbon black (CB) having high dispersibility and stability was successfully obtained by the use of poly(ethylene‐block‐ethylene oxide) (PE‐b‐PEO)‐grafted CB. The response of the electric resistance of the composite against solvent vapors was examined. The electric resistance drastically increased by 10⁴–10⁶ times the initial resistance in a nonpolar solvent vapor such as cyclohexane, and carbon tetrachloride vapor at 40 °C and returned immediately to its initial resistance when the composite was transferred to dry air. However, the electric resistance increased only several times in the polar solvent vapor, such as water and alcohol, at the same temperature. The responsiveness of electric resistance is excellently reproducible and is also stable in cyclohexane vapor and dry air. The effect of temperature on the responsiveness against cyclohexane vapor is also discussed. It is concluded that the composite of LDPE filled with PE‐b‐PEO‐grafted CB could be a promising material to use when preparing gas sensors. Copyright © 2000 John Wiley & Sons, Ltd.     

Synthesis and characterization of fluorinated benzoxazole polymers with high Tg and low dielectric constant

Next generation microelectronic packaging requirements are driving the need to produce increasingly lower dielectric constant materials while maintaining high thermal stability and ease of processing. Efforts have focused on the synthesis and analysis of new polymers with the goals of high thermal stability [degradation temperature (T_d) > 400 °C, low glass‐transition temperature (T_g) > 350 °C], low water uptake (<1%), solubility in selected organic solvents, dielectric constant less than 2.5, and low thermal expansion coefficient. These stringent combined goals have been largely achieved with flexible aromatic benzoxazole polymers. Intramolecular hydrogen bonding between pendant hydroxyl groups and the double‐bond nitrogen of the benzoxazole has been exploited to increase the polymer T_g, whereas the incorporation of perfluoroisopropyl units effectively decreases the dielectric constant. Out‐of‐plane impedance measurements on films of materials in this family (38–134 μm thick) have resulted in typical dielectric values of 2.1–2.5 at 1 MHz, depending on copolymer ratios and functionalizations. Results have been correlated with optical waveguide measurements of films 4‐μm thick to determine film anisotropy and the high‐frequency dielectric constant, and have been corroborated by in‐plane interdigitated electrode dielectric measurements on samples 0.75 μm thick. Candidate materials exhibited extremely low water uptake (0.2%) even after submersion in boiling water for several days. Dynamic mechanical analysis of the polymers enabled the determination of the influence of intermolecular hydrogen bonding on the T_g and loss tangent magnitude. Finally, the coefficient of thermal expansion has been examined and correlated with copolymer constitution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1991–2003, 2000     

注水开发工艺技术应用分析

低渗透油藏开发难度极大,主要表现在自然产能很低,甚至没有自然产能,不采用增产措施,根本无法投产,更谈不上正常开发。合理高效地开发低渗透油藏需要建立有效驱替压力系统,这是提高低渗透油气田开发的关键问题。 面对这一现状,本文首先研究论述了低渗透油藏在学术上的界定范围、分类以及在我国的分布状况,并介绍了低渗透油藏的地质特征、开发特征以及保证油藏有效开发的注水工艺技术;然后根据注水开发中存在的一系列问题提出了低渗透油藏分层注水开发的可行性,并对目前我国正在应用的分层注水工艺技术进行了介绍;最后本文以长庆油田为例对分层注水工艺技术进行分析并评价其应用效果。     

Four‐terminal reducibility and projective‐planar wye‐delta‐wye‐reducible graphs

A graph is YΔY‐reducible if it can be reduced to a vertex by a sequence of series‐parallel reductions and YΔY‐transformations. Terminals are distinguished vertices, that cannot be deleted by reductions and transformations. In this article, we show that four‐terminal planar graphs are YΔY‐reducible when at least three of the vertices lie on the same face. Using this result, we characterize YΔY‐reducible projective‐planar graphs. We also consider terminals in projective‐planar graphs, and establish that graphs of crossing‐number one are YΔY‐reducible. © 2000 John Wiley & Sons, Inc. J Graph Theory 33: 83–93, 2000