The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation

A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In this model, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. The interfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with the increase of amphiphile concentration and the decrease with temperature.

Synergistic Effect of Amphiphiles at Oil-Water Interface: By Monte Carlo Simulation

Amphiphile-oil-water system is complicated. The real behavior of amphiphile in the interface is still undnown despite that this behavior is very important in determining the stability of emulsion system. In this paper, the interface properties of amphiphile at oil-water interface were investigated by a square-lattice model Monte Carlo simulation method. The synergistic effect was found for hydrophobic and hydrophilic amphiphile mixture systems; and the synergistic effect disappears or was weakened as the amphiphile at the interface region became dilute with the increasing of temperature.

Multifractal analysis of inclined oil-water countercurrent flow

Characterizing countercurrent flow structures in an inclined oil-water two-phase flow from one-dimensional measurement is of great importance for model building and sensor design.Firstly,we conducted oil-water two-phase flow experiments in an inclined pipe to measure the conductance signals of three typical water-dominated oil-water flow patterns in inclined flow,i.e.,dispersion oil-in-water pseudo-slug flow （PS）,dispersion oil-in-water countercurrent flow （CT）,and transitional flow （TF）.In pseudo-slug flow,countercurrent flow and transitional flow,oil is completely dispersed in water.Then we used magnitude and sign decomposition analysis and multifractal analysis to reveal levels of complexity in different flow patterns.We found that the PS and CT flow patterns both exhibited high complexity and obvious multifractal dynamic behavior,but the magnitude scaling exponent and singularity of the CT flow pattern were less than those of the PS flow pattern; and the TF flow pattern exhibited low complexity and almost monofractal behavior,and its magnitude scaling was close to random behavior.Meanwhile,at short time scales,all sign series of two-phase flow patterns exhibited very similar strong positive correlation; at high time scales,the scaling analysis of sign series showed different anti-correlated behavior.Furthermore,with an increase in oil flow rate,the flow structure became regular,which could be reflected by the decrease in the width of spectrum and the difference in dimensions.The results suggested that different oil-water flow patterns exhibited different nonlinear features,and the varying levels of complexity could well characterize the fluid dynamics underlying different oil-water flow patterns.

DEVELOPMENT OF A PRECISE ELECTRO CHEMICAL INTERFACE

Based on the circuit principle of 1186 Electro Chemical Interface preduced by Solartron Electronic Group Ltd., a precise electro chemical interface (ECI) unit, which can provide the interfacing requirements for the control and measurement of characteristics of electro chemical cell, was developed by means of some essential improvements. Not only can it be used to control and measure the steady and non-steady state characteristics, but also it can be directly connected with Solartron 1170 series or 1250 Frequency Response Analysers (FRA) to measure the AC impedance. Besides,the EC1 can also be connected with two- or three-electrode electro chemical cell systems to test convenlently and correctly their DC and AC characteristics, and used as a four-electrode potentlostat combined with four-electrode electro chernical cell system which contains two reference electrodes (RES) for researches on the electro chemical characteristics of oil-water interface, etc.

Numerical parametric study on the influence of location and inclination of large-scale asperities on the shear strength of concreterock interfaces of small buttress dams

When assessing the sliding stability of a concrete dam,the influence of large-scale asperities in the sliding plane is often ignored due to limitations of the analytical rigid body assessment methods provided by current dam assessment guidelines.However,these asperities can potentially improve the load capacity of a concrete dam in terms of sliding stability.Although their influence in a sliding plane has been thoroughly studied for direct shear,their influence under eccentric loading,as in the case of dams,is unknown.This paper presents the results of a parametric study that used finite element analysis(FEA)to investigate the influence of large-scale asperities on the load capacity of small buttress dams.By varying the inclination and location of an asperity located in the concrete-rock interface along with the strength of the rock foundation material,transitions between different failure modes and correlations between the load capacity and the varied parameters were observed.The results indicated that the inclination of the asperity had a significant impact on the failure mode.When the inclinationwas 30
and greater,interlocking occurred between the dam and foundation and the governing failure modes were either rupture of the dam body or asperity.When the asperity inclination was significant enough to provide interlocking,the load capacity of the dam was impacted by the strength of the rock in the foundation through influencing the load capacity of the asperity.The location of the asperity along the concrete-rock interface did not affect the failure mode,except for when the asperity was located at the toe of the dam,but had an influence on the load capacity when the failure occurred by rupture of the buttress or by sliding.By accounting for a single large-scale asperity in the concrete-rock interface of the analysed dam,a horizontal load capacity increase of 30%e160%was obtained,depending on the inclination and location of the asperity and the strength of the foundation material.

软硬地层接触面倾角对盾构隧道纵向力学性能的影响

针对现有盾构隧道纵向力学性能研究中较少考虑纵向穿越软硬变化地层,且接触面倾角影响规律尚不清晰的问题,基于实际工程建立盾构隧道-地层三维纵向精细化模型,并提出一种同时考虑管片错缝拼装、纵环向螺栓、地层与隧道接触面真实力学性能的精细化模拟方法;采用改进的Timoshenko梁理论验证模型可靠性,并分析穿越软硬变化地层盾构隧道的纵向力学性能,探讨地层接触面倾角的影响规律。结果表明:盾构隧道沉降量在软硬地层接触面急剧变化并在软硬地层两端趋于稳定,隧道两侧沉降差异在倾角为30°和150°时更为显著;管片张开和错台量集中分布于软硬地层接触面附近,分布范围随倾角增大逐渐向软土层侧移动,最大管片张开和错台量在倾角120°时最大,分别为0.183和1.270 mm;倾角对盾构隧道纵向内力影响较大,大于90°后影响逐渐显著;纵向上,管片纵向螺栓和地层-隧道接触面的变形更为显著。研究结果可为进一步发展盾构隧道纵向分析方法和保障此类盾构隧道的安全运营提供参考。

冰岩组合体动态力学特性及裂纹演化特征研究

人工冻结法的富水基岩凿井掘进施工时,人工地下冰与岩体黏结面常受动态冲击作用影响,其稳定性决定了地下工程施工安全。为研究冰—岩复合结构的动态力学性能,采取PFC-FLAC耦合方法构建了SHPB加载系统,分析了冰岩组合体的动态特性与破坏特征,研究了试件微裂纹演化规律。结果表明:组合体试件的动弹性模量受冰岩交界面倾角θ影响较小;动载作用下组合体试件岩石中裂纹从入射端逐渐向冰岩交界面扩展,最终形成与加载方向平行的贯通主裂纹,微裂纹扩展“引导”了组合体的损伤过程;组合体试件的最终破坏形式表现为张拉与剪切复合破坏,其中岩石部分的破坏特征主要受θ影响;θ为0°~45°时,峰值应力相差不大;θ为45°~90°时,峰值应力随着θ升高呈增大趋势。

桩−土界面倾角和含水率对抗滑桩的阻滑效应分析

为研究不同界面倾角及含水率对桩–土界面的阻滑效果,首先基于变倾角组合体三轴不固结不排水试验,比较了不同界面倾角和含水率条件下变倾角组合体破坏模式和抗剪强度的差异性,然后结合室内试验抗剪强度参数,通过数值模拟方法比较不同界面倾角和含水率对桩–土界面的阻滑效果,并基于塑性变形理论确定临界含水率w_(max),最后依托工程案例对抗滑桩截面进行优化。结果表明:界面倾角和含水率是导致变倾角组合体破坏模式和抗剪强度差异的主要原因,当含水率较低时,适当增大倾角能提高组合体试样的抗剪强度;当土体含水率较小时,随着桩侧倾角的增大,桩–土界面阻滑效果呈现先增加后降低趋势,当桩侧土体含水率较高时,桩–土界面倾角越大,桩–土界面阻滑越小;当考虑桩间土拱效应时,适当增加抗滑桩桩背受压区三角形截面,作用在桩侧摩擦拱上的等效集中荷载最大可降低33%左右。相关研究成果对抗滑桩的设计具有借鉴意义。

南极冰岩界面钻进过程孔斜规律研究及调控装置设计

南极冰层下基岩取心,对于研究南极冰川形成的历程和全球气候变化等方面具有重要的意义。钻遇冰层和岩层的倾斜交界面时,极易发生孔斜,影响基岩取心的质量甚至成败。本文分析了钻头在冰岩界面钻进过程中的受力状态,探究了地层倾角、钻压、转速、机械钻速、单位体积切削功等因素对钻头受力及孔斜规律的影响。最后,基于满眼防斜的原理设计了针对冰岩界面防斜的垂直入岩装置。

含预应力锚杆煤岩组合体破坏及声发射特征试验研究

为探究预应力锚杆对煤岩组合体的锚固效应,开展了4组不同界面倾角(15°、30°、45°、60°)含预应力锚杆与仅含锚杆组合体的单轴压缩室内模拟试验,从试样破坏形态、应力-应变曲线特征及声发射参数特征3方面探讨了含预应力锚杆组合体的力学响应。结果表明:含预应力锚杆组合体残余强度与峰值强度的比值更高,预应力的施加使峰值应力前组合体能量释放增加,有效抑制了峰后能量释放,减少了组合体发生滑移破坏时与锚杆接触面的损伤,同时降低了应力波动的发生频次。含预应力锚杆与仅含锚杆组合体低频高幅信号占比随荷载的施加均呈阶段性变化特征,在组合体发生滑移时,施加在锚杆中的预应力抑制了加载初期低频高幅信号的集中;在各界面倾角下,含预应力锚杆组合体低频高幅信号占比及其标准差均更低,表明预应力锚杆有效抑制了组合体峰前内部裂纹的萌生,且降低了组合体内部裂纹演化对界面倾角变化的敏感性。

Numerical modeling of the critical pipeline inclination for the elimination of the water accumulation on the pipe floor in oil-water fluid flow

In this work,numerical models were developed to investigate the critical inclination of a pipeline to eliminate the water accumulation at the floor of the pipe carrying oil-water fluid.Computational fluid dynamics software was used to establish a geometric model of the pipe with various inclination angles,and a grid-independent verification was conducted to determine a reasonable meshing method.Quantitative relationships were determined between the pipe inclination angle and the affecting factors including the flow velocity,viscosity and the pipe diameter,where the water accumulation would not be able to occur.Generally,the critical inclination angle increases with the fluid flow velocity.The refluxing of water is the key mechanism causing the water accumulation at the bottom of the pipe.In addition to the fluid flow velocity,an increase in fluid viscosity and a decrease in the pipe diameter cause an increase of the critical inclination angle that the water phase can be carried away by oil.The model can be used to determine the critical inclination of pipelines carrying oil-water fluid to cause the water accumulation and the operating conditions that can eliminate the accumulation of water phase at the pipe floor.

基于FLAC3D的斜锚短桩抗拔静载试验模拟桩岩接触面参数影响研究

斜锚短桩基础是一种主要应用于山区输电线路的新型输电塔基础,主要由短桩基础及锚杆结构组成,较传统桩基础更具经济性和环保性,且应用范围更广,但国内外对其研究较少,在数值模拟分析中,桩-岩体接触面单元参数难以准确取值。采用三维连续介质拉格朗日法有限差分软件(FLAC3D)建立计算模型,控制改变接触面单元粘聚力c、内摩擦角φ,以探究接触面单元参数对模拟计算结果的影响。结果表明:接触面单元黏聚力c及内摩擦角φ均对计算结果有影响,其中黏聚力c为主要因素。

大直径长桩接触面参数的敏感性分析

基于FLAC3D数值分析软件,探讨了大直径长桩的数值模拟方法,分析了桩土间接触面参数对数值计算结果的影响。结果表明:桩侧接触面的内摩擦角和粘聚力对桩的承载性能影响较大,而剪切刚度的影响存在一临界值;水平荷载下,需考虑桩侧接触面参数对桩与桩侧土体之间摩阻力的影响;竖向荷载下,需考虑剪切刚度随深度的变化;倾斜荷载下,需考虑桩端土的剪切作用。

柴达木盆地第四系倾斜式气藏的形成机理

柴达木盆地涩北1号气田的气水界面不是一个水平面,呈现向北东倾斜的斜面,气田东北翼的气水边界比西南翼低30余米。其形成机理是,来自西南方昆仑山的地层水流经涩北1号气田,并在东北方向露头区渗出,在独立的流体流动系统内形成的水动力压差,导致涩北1号气田的气水界面发生倾斜(约0.5°),气水界面与构造等值线不一致,称其为气水界面倾斜式气藏。这类气藏的研究对该区天然气勘探、含气面积、储量计算和开发井网部署等方面的研究都有密切的关系。

两相材料倾斜裂纹的界面应力场

采用 Muskhelishvili复变函数的方法 ,将两相材料倾斜裂纹问题归结为以裂纹表面位错密度函数为未知量的 Cauchy型奇异积分方程的求解 .通过 Cauchy型奇异积分的主部分析 ,得到倾斜裂纹接触界面时性态指数的特征方程 ,给出的数值结果可对奇异积分方程进行数值求解 .根据两相材料倾斜裂纹在界面上产生的应力场与位错密度函数的关系 ,得到界面常规应力场及奇性应力场表达式 .最后对两相材料的界面应力场进行了数值求解和分析 。

近钻头随钻伽马成像快速正弦曲线拟合方法

针对现有随钻测井数据传输速率较低的问题和井下实时获取伽马成像图的需求,模拟分析了近钻头伽马成像测井仪器穿过倾斜界面进入高放射性泥岩层的扇区成像特征,提出了基于扇区伽马成像图的快速正弦曲线拟合方法。设计了近钻头伽马成像测井中的快速正弦曲线拟合固件算法,将最小二乘估计算法和三参数正弦拟合相结合,提取得到正弦曲线的幅度、频率、相位和直流分量等4个参数,为拟合反演形成多扇区伽马成像图提供数据。利用快速正弦曲线拟合方法,测试了用标准岩样构造分层倾斜地层模拟井眼采集的伽马数据,实现了多扇区伽马成像测量值的拟合,且拟合误差较小。研究结果表明,拟合反演得到的8扇区伽马成像图的正弦曲线特征明显,能够准确反映倾斜地层界面信息,验证了快速正弦曲线拟合方法的可行性和正确性。

矿井斜巷乘人装置智能运行系统的研制

文章介绍了一种由人机界面和PLC及相应传感器等组成的矿井斜巷乘人装置智能运行系统,分析了该系统的硬件结构、运行方式、保护功能和主要特点,给出了智能运行系统的软件设计。该系统为矿井斜巷乘人装置的安全、高效运行提供了可靠保障。

大型斜面剪切仪的研制和试验

位于垃圾填埋场斜坡上的衬垫结构在垂直应力作用下沿斜坡滑移的剪切状态与底坡上衬垫结构的不同,为了模拟斜坡上衬垫结构间剪切特性,研制了斜面剪切仪。通过对标准砂和黏土的大型斜面和普通直剪剪切试验,发现两种试验得到的标准砂和黏土剪切应力位移特性基本相同,强度指标也相同。在此基础上,进行了光面HDPE土工膜与黏土复合衬垫界面斜面剪切试验,得到的剪应力与正应力比–位移曲线均有峰值和峰值后的软化现象。斜面剪切试验的特点是能够得到剪切面上法向应力和剪切应力同时增加的变化规律,可以揭示更详细的剪切特征,这有利于分析剪切过程中剪切面上法向应力和剪切应力的特性,如剪切面上法向应力和剪切应力变化规律以及剪切面上法向应力和剪切应力比的变化规律。

单颗种植体支持单冠的不同牙尖斜度设计的三维有限元分析

用三维有限元法对单颗种植体支持单冠在不同牙尖斜度(25°、35°、45°)及不同载荷条件下(150、300N)的应力进行分析。用螺旋CT扫描下颌骨,在数字化仪中读取下颌骨各边缘及种植体边缘,将读取数据编成ANSYS程序文件,进行三维重建及网格划分,按照咀嚼力均值加载并进行受力分析。在种植体颈部及根端舌侧为应力集中区,牙尖斜度为25°时VonMises应力最小。单颗种植体支持单冠受力时应力集中在种植体颈部的骨皮质及种植体根端区,牙尖斜度为25°时VonMises应力最小且不会引起骨整合界面的破坏。

垂直及倾斜接触面电测深曲线特征

在实际应用中,层状介质往往有一定的倾斜角度,利用经典理论中的解析法求解水平地层上的视电阻率测深曲线有一定的局限性。而只有当反射系数为"1",倾斜角度为π/m;或反射系数为"-1",倾斜角度为π/2m时(m为整数),才能利用镜像法来求解倾斜接触面上的视电阻率。这里推导了倾斜接触面存在时电测深视电阻率的计算公式,给出了任意倾斜角度的接触面上测深视电阻率曲线特征,并讨论了垂直接触面上装置轴与接触面平行、斜交及垂直时视电阻率曲线的变化情况,较好地解决了陡倾接触面旁侧电阻率法推断解释中的一些实际问题。