Experiments on the hydrodynamics of air-water countercurrent flow through vertical short multitube geometries

A series of experiments were performed to improve understanding of the hydrodynamic mechanisms relevant to the flooding phenomenon in gas-liquid countercurrent flow through vertical short multitube geometries. In addition to the conventional measurements of global hydrodynamic parameters such as phasic flow rates and two-phase pressure drops, the local time-varying thicknesses of the liquid films trickling down the individual tubes were measured by means of conductance probes mounted flush at different locations of the inner wall surfaces. A PC-based data acquisition and analysis system was developed to collect these highly fluctuating data and to make detailed statistical analyses. The experimental results and visual observations revealed two dominant hydrodynamic instability mechanisms that have not been well taken into account by the existing semiempirical models.     

Application of response surface methodology for optimization of the stability of asphaltene particles in crude oil by TiO2/SiO2 nanofluids under static and dynamic conditions

In this work, the onset of asphaltene flocculation for an Iranian crude oil by titration of samples with heptane in the presence and absence of the TiO₂/SiO₂ nanofluids was obtained by Near-IR spectroscopy. Nanoparticles and nanocomposites were characterized by BET, FESEM, EDX, XRD, and XRF analysis. Modeling and optimization of inhibition of asphaltene flocculation process by TiO₂/SiO₂ nanofluids were conducted by response surface methodology (RSM). Under optimum conditions (nanocomposite composition = 0.04 wt% (80%TiO₂:20%SiO₂), salinity = 4.01 wt%, and pH = 3.42), the onset point increased. For nanofluids stability analysis, the optimum nanofluid was compared with the two other nanofluids (SiO₂ and TiO₂) by visual observation method. The results indicated that high stability and surface area of the 80%TiO₂ nanocomposites increase asphaltene adsorption on the particles surface that subsequently increases the onset point. In addition, the optimum nanofluid performance on the carbonate rocks was evaluated by contact angle and core flooding experiments. The 80% TiO₂ nanofluid changed the wettability of carbonate rocks from strongly oil-wet to strongly water-wet condition and also decreased the residual oil saturation and enhanced the oil recovery with an increase in the recovery factor of about 15%.     

Virtual machine co-residency method on cloud computing platform

If the attacker wants to compromise a target virtual machine on a cloud platform,the malicious virtual machine must be co-resident with the target.Based on this,a virtual machine co-residency method was proposed.The method combined a co-residency detection scheme based on covert channel construction and an automatic virtual machine flooding strategy,and was evaluated on a well-known domestic cloud platform.Experiment shows that the adaptive covert channel can achieve accuracies of 95%,the proposed detection scheme has strong robustness whose false positive rate is less than 5 ‰,the proposed method is versatile and keeps the virtualization isolation barrier intact,which has great potential threat and should be paid great attention and precaution.     

基于华为ENSP和Vmware Workstation软件模拟MAC洪泛攻击与防御的实验综述报告

通过VMware Workstation模拟操作系统、华为eNSP模拟网络环境组成的模拟环境对学生直观的讲解攻击的过程和如何防御,加深学生对交换机原理的理解。同时可以有效解决实验室设备数量功能等受限的问题,方便学生随时学习掌握。教学效果得到了很大的提升。     

表面活性剂疏水链长对高温下泡沫稳定性的影响

选用不同疏水链长的α-烯烃磺酸盐(AOS)形成泡沫, 分别用泡沫衰减法和泡沫岩芯封堵法测定不同温度下的泡沫稳定性, 并采用动态表面张力、界面流变、分子模拟等方法研究了表面活性剂在气/液界面的吸附行为和界面吸附层的性质, 分析了高温下泡沫的稳定机制. 实验结果表明, 在高温下, 极性头的“锚定作用”减弱, 表面活性剂疏水链难以在气液界面保持以直立状态吸附, 疏水链碳数大于20的表面活性剂分子难以分立吸附, 其疏水链相互交叉缠绕, 增强了泡沫膜的强度, 减缓了气体通过液膜的扩散, 形成的泡沫在高温下具有较好的稳定性.     

枸杞子中红色素的提取及稳定性

枸杞子中红色素的提取及稳定性伍明，王杰，闪春霞，任仲皎，宋锡瑾，詹国庆（中南民族学院化学系武汉４３００７４）关键词枸杞，色素，液泛提取法枸杞子为茄科枸杞属植物的果实，具有补肾养肝，润肺明目以及调节机体免疫力，抑制肿瘤生长和细胞突变，延缓衰老及抗脂肪肝...     

P2P对等网络路由模型及关键技术分析

介绍了P2P网络的技术发展,详细分析了4种典型的P2P网络结构,论述了P2P网络发展的关键技术,对P2P网络的特性以及存在的问题进行了探讨,为P2P网络更深层次的应用奠定基础。     

聚驱后油田剩余油潜力分布规律研究

综合考虑剩余油饱和度、厚度、渗透率、孔隙度、相带、原始含油饱和度、注水井距离等7个因素,利用模糊综合评价方法,以大庆油田北一二排西块为例,计算了该区块8个沉积聚驱后剩余油潜力,并分析聚驱后剩余油潜力分布特征.结果表明,聚驱后仍有比较大的剩余油潜力;聚驱后剩余油潜力主要集中在高渗透、厚度较大、剩余油饱和度较高、河道砂等高级别沉积相带的区域;聚驱后在潜力值为0～0.2区间内的剩余油储量很小,潜力值为0.4～0.6区间内的剩余油储量最大,而潜力值为0.6～0.8区间内剩余油储量次之.     

特低渗油藏不同开发方式室内实验研究

把特低渗透油藏岩心根据渗透率划分为不同等级,分别对不同等级岩心进行注水、注氮气和注二氧化碳室内实验.测得了不同开发方式条件下注采压差梯度和洗油效率,回归出不同开发方式下洗油效率随渗透率变化关系式,并对不同开发方式效果进行对比分析.研究结果表明:特低渗油藏在不同方式开发过程中,注入压力都表现为先上升后下降,最后趋于稳定值...     

聚(丙烯酰胺-丙烯酸)/聚(丙烯酰胺-二甲基二烯丙基氯化铵)分子复合型聚合物驱油剂的增粘作用

通过Brookfield粘度测定及室内岩心驱油试验评定,研究了聚(丙烯酰胺－丙烯酸)/聚(丙烯酸胺－二甲基二烯丙基氯化铵)[P(AM－AA)/P(AM－DMDAAC)]分子复合型聚合物驱油剂的增粘、抗温、抗盐性及其驱油效果.结果表明：聚合物组成一定时,其复合比影响溶液复合增粘效果;复合型聚合物溶液的抗盐性明显优于P(AM－AA)溶液的抗盐性;多价金属离子的加入是提高溶液抗盐性的有效途径.该驱油剂的最终采收率达61.91％.