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关键词： 高密度聚乙烯(HDPE)防水卷材   丁腈胶粉   硅橡胶   力学性能   尺寸稳定性   表面张力   线膨胀系数  

摘要： 通过添加丁腈胶粉或硅橡胶组分来改善高密度聚乙烯(HDPE)防水卷材的尺寸稳定性,研究了橡胶组分用量对卷材力学性能、结晶性能、表面张力及线膨胀系数的影响。结果表明,适量的橡胶组分与HDPE相容性较好,能在一定程度上改善卷材的力学性能、结晶性能;随着橡胶组分用量的增加,卷材的线膨胀系数降低,尺寸稳定性提高;硅橡胶用量的增加使得卷材的表面张力下降,防水性能提高。

关键词： 表面活性剂   表面张力   泡沫性能   界面张力   乳化性  

摘要： 以对苯二胺、棕榈酰氯、2-氯乙基磺酸钠为主要原料,经取代和酰化等反应合成了一种磺酸盐型双子表面活性剂——N,N'-双棕榈酰基对苯二胺二乙基磺酸钠(DS16-P-16),用FTIR、~1HNMR对中间体和目标产物进行了结构表征,并测定了其水溶性、表&界面活性、泡沫性能和乳化性能。结果表明:在25℃时,DS16-P-16的临界胶束浓度(CMC为5.01×10^(-4) mol/L)是传统表面活性剂十二烷基硫酸钠(SDS)的6.26%,pC20(水的表面张力降低20 mN/m时所需溶液浓度的负对数)为3.61,表现出更好的降低水表面张力的效率;随着温度和溶液浓度的增大,DS16-P-16溶液与吉林油田原油的界面张力逐渐降低,且均低于1×10^(-2) mN/m,在45℃下,质量分数为0.5%的该溶液可将油水界面张力降低至1.46×10^(-2) mN/m;在质量分数为0.1%时,DS16-P-16溶液的初始起泡高度为28 cm,稳泡率可达93%,乳状液稳定时间为437 s。相同条件下,质量分数为0.1%的十二烷基硫酸钠的初始起泡高度为15 cm,稳泡率为60%,乳化时间为128 s。

关键词： 肥皂膜   表面活性剂   金属环   表面张力  

摘要： '肥皂泡泡'对于我们来说一点都不陌生,或者自己吹过或者看见别人吹过。那多彩斑斓的泡泡,漫天飞舞,煞是好看。有的朋友不但吹过泡泡,还自制过肥皂水吧?把肥皂浸泡在水里,得到肥皂水,再找来一根吸管,就可以吹出非常有意思的肥皂泡泡。可能我们会觉得吹泡泡非常简单,不就是水中加点儿肥皂或洗涤灵嘛。其实,肥皂泡泡中蕴藏着很多科学道理。单纯的水为什么吹不出泡泡?水中加入肥皂或洗涤灵为什么就可以吹出泡泡?外壁透明的泡泡为什么会呈现五颜六色?带着这些问题,我们一起来研究一下这个随手可得却又不寻常的肥皂泡泡吧。

关键词： 水基渗透剂   渗透能力   表面张力   粘度   润湿能力  

摘要： 以溶剂去离子水、粘度调节剂1,2-丙二醇和表面活性剂开发新型环保水基渗透剂,分析对比5种有代表性的非离子表面活性剂的实际效果,择优后确定渗透剂的物质组成,并探究通过调整组分配比来调控该渗透剂性能的方法。结果表明:在涉及的5种表面活性剂中,AEO-7具有最好的综合性能;渗透剂的粘度、表面张力、润湿能力和渗透能力均可通过改变1,2-丙二醇和AEO-7的用量来调控;选择合适配比自制水基渗透剂,其渗透效果高于市售产品。

关键词： 海洋水文学   风生流场   速度势   流函数   时空模态   REOF分析   渤海   黄海  

摘要： 根据1975—2017年冬、夏季节渤、黄海沿岸25个气象站风观测资料,采用二维非线性垂直平均风生流模式、旋转经验正交函数(REOF)等方法,研究了渤、黄海冬、夏季节平均风生流速度势与流函数场年际变化时空模态与环流变异.由于冬、夏季节渤、黄海风应力场强度年际变化显著线性减弱趋势,冬季渤、黄海平均速度势与流函数强度年际变化线性减弱速率大于夏季,黄海冬、夏季平均速度势与流函数强度年际变化线性减弱速率大于渤海.渤、黄海冬、夏季节平均风生流速度势与流函数场年际变化主要有两种时空模态,冬季渤海垂直环流显著线性减弱以及水平环流准平衡态年际变化是主要分量,冬季黄海垂直与水平环流准平衡态年际变化是主要分量.夏季渤海垂直环流显著线性减弱以及水平环流准平衡态年际变化是主要分量,夏季黄海大部分海域垂直环流显著线性减弱与局部垂直环流显著线性增强年际变化是主要分量,夏季黄海水平环流形态此消彼长显著线性增强及减弱年际变化是主要分量.冬季黄海暖流暖水向南黄海西侧以及向渤海中部输送过程是在3～4个环流之间传递形成,并非由单一环流输送形成.冬季渤海中部辐散下沉反气旋环流与黄海中部至渤海海峡的气旋环流、黄海东部辐散下沉反气旋环流是冬季黄海暖流强度与范围的控制环流,夏季渤海中部辐散下沉反气旋环流与黄海中部辐合上升气旋型环流是夏季渤、黄海冷水团强度与范围的控制环流,冬、夏季节渤、黄海控制环流年际变化形态的变换形成冬季黄海暖流与夏季渤、黄海冷水团暖年或冷年的年际变化.

关键词： 油气层分布   流体性质   构造活动   主控因素  

摘要： 以完钻井资料和岩心化验分析资料为基础,对研究区油气层分布特征及流体性质进行研究。结果表明:该块油气主要分布在东二段,油气分布受多重因素控制,油气水关系复杂,无统一油水界面,油藏类型为岩性构造油气藏。KD1块原油密度和黏度随深度增加而逐渐减小,具有凝固点较低,含蜡量低,胶质+沥青质含量较高的特点;KD8块原油性质变化不大,具有密度小、黏度低的特点,其油品为轻质常规油。地层水类型为NaHCO3型。

关键词： Yang-Laplace公式   液桥   边缘提取   表面张力系数  

摘要： 基于Yang-Laplace公式与液桥平均曲率的关系,研究两平行板间液桥的形貌与表面张力系数的关系,探索出通过对液桥边缘进行轮廓拟合来测量液桥液体的表面张力系数的方法.搭建了一套可以拍摄液桥的边缘放大图的实验平台,利用sobel算子提取边缘信息的Matlab算法,对液桥轮廓进行边缘提取,进而拟合得到液体表面张力系数,计算结果显示表面张力系数的相对误差在5%以内.

关键词： Ba(Fe1-xCox)(2)As-2 superconductor   s-wave energy gap   d-wave energy gap   Two-gap model   Penetration depth   Optical conductivity  

摘要： The temperature and frequency dependence of complex dynamical conductivity sigma = sigma(1) + i sigma(2), penetration depth, and superfluid density of Ba(Fe1-xCox)(2)As-2 are calculated in the framework of one- and two-gap models at terahertz frequencies for a temperature range of 2 K < T < T-C (T-C = 22 K). In the single-gap model, an isotropic s-wave gap without any node and a d-wave gap with possible nodes are considered. In the two-gap model, one of the gaps was considered isotropic s-wave gap with amplitude Delta(A)=3 meV, while the other gap was supposed to be an anisotropic d-wave gap with possible nodes, and its rms amplitude was Delta(0) = 8 meV. The interaction between the gaps is waived, since it is small, and its description is problematic. Comparing the result with the experimental data proves that the two-gap model consistently describes the optical characteristics of Ba(Fe1-xCox)(2)As-2. In the two-gap model, the temperature dependence of sigma(1) demonstrated a coherence peak at frequencies below 15 cm(-1). The temperature dependence of the penetration depth calculated from sigma(2) shows power-law behavior at low temperatures, and the superfluid density varies steeply near T-C.

关键词： Flow instabilities   Cardiovascular system   Flow simulations   Heart rate   Fluid mechanics   Covariance and correlation   Newtonian fluids   Haemodynamics   Navier Stokes equations   Vortex dynamics  

摘要： A simple parameter, called the Aneurysm number (An) which is defined as the ratio of transport to vortex time scales, has been shown to classify the flow mode in simplified aneurysm geometries. Our objective is to test the hypothesis that An can classify the flow in patient-specific intracranial aneurysms (IA). Therefore, the definition of this parameter is extended to anatomic geometries by using hydraulic diameter and the length of expansion area in the approximate direction of the flow. The hypothesis is tested using image-based flow simulations in five sidewall and four bifurcation geometries, i.e., if An less than or similar to 1 (shorter transport time scale), then the fluid is transported across the neck before the vortex could be formed, creating a quasi-stationary shear layer (cavity mode). By contrast, if An greater than or similar to 1 (shorter vortex time scale), a vortex is formed. The results show that if An switches from An less than or similar to 1 to An greater than or similar to 1, then the flow mode switches from the cavity mode to the vortex mode. However, if An does not switch, then the IAs stay in the same mode. It is also shown that IAs in the cavity mode have significantly lower An, temporal fluctuations of wall shear stress and oscillatory shear index (OSI) compared to the vortex mode (p < 0.01). In addition, OSI correlates with An in each flow mode and with pulsatiity index in each IA. This suggests An to be a viable hemodynamic parameter which can be easily calculated without the need for detailed flow measurements/ simulations. Published under license by AIP Publishing.

关键词： Friction factor   Explicit solutions   Moody diagram   Maximum deviation   Turbulent flow  

摘要： The Colebrook-white equation is widely used in many fields, like civil engineering for calculation of water distribution systems and in all fields of engineering where fluid flow can be occurred. Numerous formulas have been proposed since 1947 in order to simplify the computation of the friction factor, to avoid the iterative procedures methods and to alter the Colebrook-white equation in practice. most of the existing explicit formulas for computation of the friction factor for turbulent flow in rough pipes proposed are cited, where thirty three "33" equations have been inventoried. The goal of this paper is to assess the accuracy of each model and to propose an arrangement from the best to the lower accuracy according to a proposed method combined of three criteria which are: simplicity of the formula, maximum deviations and the coverage of the entire range of Moody diagram. (C) 2019 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, Ain Shams University.