Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water

A super-hydrophilic functional ceramic was prepared by adjusting the chemical components of ceramic glaze. Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water were studied. The results show that water can spread on ceramic surface with high surface free energy, and oil droplet can aggregate rapidly and separate from the ceramic surface in water. For the ceramic with lower surface free energy, the polar shares are dependant on its easy-cleaning property. The higher the polar shares, the better the easy-cleaning property, and the easier the droplet separates from the ceramic surface in water.

Surface free energy of copper-zinc alloy for energy-saving of boiler

Cu-Zn,Cu-Zn-Sn,Cu-Zn-Ni alloys were melted by vacuum smelter.The effect factors to the surface free energy of the alloys such as chemical composition,crystal structure and surface crystal lattice distortion etc.were investigated by OCA30 automatic contact angle test instrument,metallography microscope and XRD instrument etc.Results suggests:adding alloy element to Cu may increase its surface free energy,and the more kinds of alloy elements are added,the more surface free energy increases;the alloy element Sn an increase the surface free energy of Cu-Zn alloy;Cu-Zn alloy with fir-tree crystal structure,great phase discrepancy and obvious composition aliquation has greater surface free energy;Cu-Zn alloy with compounds and serious surface crystal lattice distortion has greater surface free energy.

Effect of ACQ-D Treatment on the Surface Free Energy of Chinese Fir (Cunninghamia lanceolata)

In this study, the contact angles of three different reference liquids （including distilled water, diiodomethane, and formamide） and PF resin on the surfaces of Chinese fir （Cunningharnia lanceolata） samples untreated or treated with different concentrations of ACQ-D （ammoniacal copper quat Type D） solutions were measured. Then, the surface free energy was calculated by two approaches： acid-base approach and geometric mean approach. ACQ-D treatment caused higher contact angles and lower surface free energies at a retention level corresponding to the commodity treated wood products. When wood was treated with much higher concentrations of ACQ-D, the total surface free energy of wood would be higher than the untreated control. Acid-base/polar components related with the hydrogen bonding state in wood were considered to be responsible for the observed changes according to the applied approaches. The hydrophobic properties and also higher contact angles of PF resin drop on wood surfaces after ACQ-D treatment at a reasonable retention level confirms the changes on surface free energy.

The Effect of Surface Properties of Biomedical Materials on Their Blood Compatibility

The effect of surface properties of six types of biomedical materials on their blood compatibility was investigated in this study. The surface roughness of biomaterials was determined by confocal laser scanning microscopy （CLSM）. The contact angle was observed by contact angle measurement （CAM）. Then the surface free energy （SFE） and interfacial free energy （IFE） were calculated by the contact angle value based on the Owens- Wendt （OW） theoretical model and Young＇ s equation. Meanwhile, hemolytic assay was employed to evaluate the haemolysis. The experimental results showed that the greater roughness was, the greater contact angle would be ; the less proportion of polar component in surface free energy （SFE） was, the lower haemolysis would be.

Super gas wet and gas wet rock surface: State of the art evaluation through contact angle analysis

Recently,super gas wet and gas wet surfaces have been extensively attended in petroleum industry,as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs.In many cases,contact angle measurement has been employed to assess the wettability alteration.Even though contact angle measurement seems to be a straightforward approach,there exist many misuses of this technique and consequently misinterpretation of the corresponding results.In this regard,a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas systems could aid to provide some remediation to alleviate this problem.To this end,this work presents a survey on the accurate terms and rigorous protocols based on the community of surface science and chemistry.As a preliminary step,advancing,receding,static,and the most stable contact angle terminology are defined.The study is followed by the definition of the contact angle hysteresis effect.The application of surface free energy in the selection of the best gas wet agent is then analyzed.Afterward,the impact of the size-dependent behavior of drop on contact angle is discussed.Finally,a sessile drop experiment is explained to achieve the defined parameters.For future contributions to petroleum industry journals,like this journal,this work could offer an easy use of the conceptual framework for analyzing the results and comparative evaluations in chemical wettability modifier agents.

基于断面水边线定向的视频测流摄像机标定

针对现有基于直接线性变化法(DLT)的图像法测流技术依赖于地面控制点,存在效率低、风险高、宽断面天然河流操作难度大等问题,该文提出一种基于断面水边线定向的摄像机姿态角标定方法(CSWO)。该方法将标定过程分解为实验室内参标定和现场外参标定两步,其中后者又被划分为摄像机定位和定向两个环节。定向环节中首先在摄像机安装时将光轴与断面方向对齐,使方位角置零。然后利用无畸变图像中人工标注的平直断面水边线的斜率计算出横滚角。接下来通过计算水边线与图像纵轴交点作为其亚像素像方坐标。最后依据透视投影成像模型,联合水位与插值断面高程求得的物方坐标解算出俯仰角。该方法应用于时空图像测速法(STIV),实现了200 m宽河流的免像控表面流速测量。结果表明:起点距的最大绝对误差为0.59 m,最大相对误差为0.45%,表面流速的最大相对误差小于6.3%。

含氟纳米乳液的制备及在储层润湿逆转中的应用

以甲基丙烯酸甲酯、丙烯酸丁酯、γ-甲基丙烯酰氧基丙基三甲氧基硅烷、全氟己基乙基丙烯酸酯(PEA)为原料,制备了一种可改变储层润湿性、防止储层水锁的含氟纳米乳液(FPA)。采用FTIR、SEM、XRD、马尔文激光粒度仪对FPA乳液进行了表征,采用表面张力、排出率、毛细管自吸、接触角测试方法考察了FPA-3(PEA质量分数为1.5%)乳液质量分数对改变岩心润湿性的影响。结果表明,PEA成功引入到聚合物链上,随着PEA质量分数的增加,乳液粒径增大,当PEA质量分数>1.5%时,乳液出现分层,FPA-3乳液稳定性最好。随着FPA-3乳液质量分数的增大,FPA-3水溶液表面张力减小,排出率增大,毛细管自吸高度减小,与水的接触角增大。当乳液质量分数均为2.0%时,与PA水溶液相比,FPA-3水溶液的表面张力由46.01 mN/m减小至22.68mN/m,降低了50.70%;排出率由19.89%增至29.47%,提高了48.16%;岩心的表面自由能由73.2 mN/m减小至8.7 mN/m;使岩心由亲水性(θ=69.8°)转变为疏水性(θ=125.1°)。质量分数为2.0%的FPA-3水溶液的毛细管自吸高度由清水的42 mm减至30 mm。

旋翼近水面效应影响因素

旋翼在近水面高速旋转产生的水气交混流场会引发近水面效应,为了解近水面效应对飞行器介质跨越造成的潜在风险,通过近水面与地面实验详细对比了不同直径的碳纤维旋翼桨叶在无地效、地面效应与近水面效应工况下的气动特性。研究分析了旋翼近水面效应关键影响因素,指出了旋翼在近水面工作时拉力、扭矩与功率剧烈变化的原因,初步认识了液滴对于旋翼的作用,揭示了近水面效应影响规律:对于直径0.56 m桨叶,在高油门、低水面距离工况下,近水面效应具有非线性增升、增阻、转速降低、需用功率增大的效果;低油门、高水面距离工况下具有增升、减阻的效果;同时近水面效应又受旋翼直径、桨叶类型、转速影响。对于直径0.25 m桨叶,在不同工况下近水面效应都具有增升、减阻的效果。

考虑宏微观几何形貌的螺栓连接结合面接触性能模型

为准确预测螺栓连接结合面的真实接触状态,提出了考虑宏微观几何形貌的螺栓连接结合面接触性能模型。通过小波分解方法,解决了实测螺栓连接结合面粗糙表面提取与重构的问题。采用两粗糙表面接触等效、数据驱动建模、宏微观变网格划分等技术,构建了考虑微观形貌与宏观几何尺寸耦合的螺栓连接结合面跨尺度模型,实现了结合面接触性能的准确计算。通过压力薄膜传感器测量被连接件结合面的压力分布,验证了计算模型的正确性,并以此为基础系统分析了被连接件厚度、螺栓预紧力以及螺栓规格尺寸对结合面接触性能的影响。计算结果表明:螺栓连接结合面真实压力分布具有非连续性,结合面压力最大值并非在被连接件孔径边缘处,而是在孔径与螺栓头外径之间;结合面真实接触面积远小于名义接触面积;结合面真实压力分布范围随着被连接件厚度、螺栓预紧力、螺栓规格尺寸的增加而增加,厚度和预紧力的影响呈现明显的非线性,螺栓尺寸的影响呈现一定的线性规律,且斜率为0.37。研究结果可为刚度、阻尼、密封等机械装备装配性能的可靠评估提供支撑。

恒定法向刚度条件下加锚充填节理岩体剪切特性研究

深部岩体节理往往存在不同程度的软弱充填物质,导致岩体力学性质更为复杂。开展恒定法向刚度CNS边界条件下,考虑高初始法向应力及不同节理粗糙系数JRC−充填度△组合模式的加锚充填节理岩体剪切试验,结合微观电镜扫描(scanning electron microscope,简称SEM)分析充填节理部分宏微观结构演变特征,推导CNS边界条件下峰值剪胀角相关计算方法。研究结果表明:当△<0.5,试件剪应力强度呈现应力硬化;当1.0<△≤1.5,剪应力强度由基本恒定演化为应力软化。当△小于临界充填度△_(cr),JRC成为峰值抗剪强度主要影响因素。△在节理法向变形中起到控制作用,随着△的增加,出现剪胀、先剪胀后剪缩、剪缩3种演化规律,JRC则影响着试件剪胀−剪缩变化程度。充填节理部分破坏模式随着△的增加主要经历3个阶段:粗糙点磨平、充填物质摩擦、充填物质磨碎。微观角度下由疏松多孔结构形式演化为散体碎屑状结构形式。受挤压破碎区与挤压应力集中区二者的相互演化机制影响,锚杆剪切变形模式逐渐由△=0的“近似”拉剪变形向△=1.5的拉弯变形模式演变。在此基础上,提出了一种CNS边界条件下加锚充填节理岩体峰值剪胀角的计算公式,并进行了试验验证及边界条件影响参数敏感性分析。

基于注意力机制的CNN-LSTM网络下肢膝关节角度预测

解析膝关节运动意图是实现下肢外骨骼机器人穿戴舒适性的核心。神经系统疾病患者常伴有下肢运动障碍,通过表面肌电信号对其进行运动评估。为实现上述患者在运动评估与关节角度预测的融合,本文提出一种新型的基于注意力机制的CNN-LSTM网络模型,通过10通道表面肌电信号实现水平行走、上坡和上楼梯时3种日常运动膝关节角度预测,其预测误差指标均方根误差(Root mean square error,RMSE)、平均绝对误差(Mean absolute error,MAE)和决定系数(R^(2))均值分别为2.74、2.50和0.97,均优于传统网络模型。进一步,通过消融实验,显示上述3个预测指标分别平均下降了20.47%、34.36%和6.59%。可见,本文提出的基于注意力机制的CNN-LSTM模型端到端预测方法具有最高的预测精度,为下肢外骨骼机器人系统的人机交互控制方案提供了参考。

基于Workbench的十字万向节的多目标优化

以煤矿用十字万向节为例,通过ANSYS Workbench有限元软件构建了十字万向节局部响应面模型,通过内置专业优化模块Design Exploration对十字万向节结构尺寸及厚度进行多目标优化设计,并给出设计推荐值。结果表明,优化后的十字万向节在降低设计重量的同时其结构强度也满足规范要求,具有较高的经济性与可行性。

基于AdaBoost-WOA-HKELM的下肢关节角度预测

针对当前下肢连续运动预测精度低的问题,提出一种基于AdaBoost-WOA-HKELM的下肢髋、膝关节角度预测方法。采集人体正常行走状态下的下肢表面肌电信号和关节角度信息,对预处理后的表面肌电信号进行特征提取,并结合关节角度信息建立特征数据集;选用混合核极限学习机(HKELM)模型作为弱学习器,引入鲸鱼优化算法(WOA)对HKELM模型参数进行优化,通过AdaBoost集成学习算法将弱学习器训练为强学习器,建立AdaBoost-WOA-HKELM关节角度预测模型,利用特征数据集对Ada⁃Boost-WOA-HKELM模型进行训练、测试,并与HKELM、WOA-HKELM模型进行髋、膝关节角度预测的仿真对比实验。结果表明:AdaBoost-WOA-HKELM模型在髋关节和膝关节角度预测方面表现出色,其均方误差分别仅为2.0869和2.2849,而决定系数分别达到了0.9882和0.9887。以上指标明显优于其他2种模型,突显了AdaBoost-WOA-HKELM模型在精确预测下肢关节角度方面的卓越性能。决定系数接近1的结果表明模型对实际数据的拟合程度极高,进一步验证了AdaBoost-WOA-HKELM模型的有效性和准确性。

Evaluation of gas wettability and its effects on fluid distribution and fluid flow in porous media

The special gas wettability phenomenon of reservoir rocks has been recognized by more and more researchers.It has a significant effect on efficient development of unconventional reservoirs.First,based on the preferentially gas-covered ability and surface free energy changes,definition and evaluation methods have been established.Second,a method for altering rock wettability and its mechanisms have been studied,surface oriented phenomena of functional groups with low surface energy are the fundamental reason for gas wettability alteration of rock.Third,the effect of gas wettability on the surface energy,electrical properties and dilatability are investigated.Last,the effects of gas wettability on capillary pressure,oil/gas/water distribution and flow are investigated with capillary tubes and etchedglass network models.The gas wettability theory of reservoir rocks has been initially established,which provides theoretical support for the efficient production of unconventional reservoirs and has great significance.

Wettability and Surface Free Energy Analyses of Monolayer Graphene

Recently Rafiee et al. experimentally demonstrated the wetting transparency of graphene, but there is still no comprehensive theoretical explanation of this physical phenomenon. Since surface free energy is one of the most important parameters characterizing material surfaces and is closely related to the wetting behavior, the surface free energy of suspended monolayer graphene is analyzed based on its microscopic formation mechanism. The surface free energy of suspended monolayer graphene is shown to be zero, which suggests its super-hydrophobicity. Neumann's equation of state is applied to further illustrate the contact angle, θ, of any liquid droplet on a suspended monolayer graphene is 180 o. This indicates that the van der Waals(vd W) interactions between the monolayer graphene and any liquid droplet are negligible; thus the monolayer graphene coatings exhibit wetting transparency to the underlying substrate. Moreover, molecular dynamics(MD) simulations are employed to further confirm the wetting transparency of graphene in comparison with experimental results of Rafiee et al. These findings provide a fundamental picture of wetting on ideal single atomic layer materials, including monolayer graphene. Thus, these results provide a useful guide for the design and manufacture of biomaterials, medical instruments, and renewable energy devices with monolayer graphene layers.

基于低分辨率DAC的IRS辅助去蜂窝大规模MIMO系统联合预编码设计

本文研究了下行链路智能反射面(Intelligent Reflective Surface, IRS)辅助去蜂窝大规模MIMO(Cell-Free Massive Multiple-Input Multiple-Output)系统,其中每个接入点(Access Point, AP)都采用了低分辨率的数模转换器(Digital-to-Analog Converters,DAC)。本文将IRS应用于去蜂窝系统并在AP处配备低分辨率DAC,进一步降低了硬件成本和功耗。采用加性量化噪声模型对低分辨率DAC进行数学建模,进而建立了下行链路用户和速率的表达式。由于公式具有非凸性和高复杂性,本文提出了一个交替优化框架来解决此问题,从而提高用户和速率。特别地,我们通过分数规划解耦这个问题,并采用拉格朗日乘子法和半定规划(Semi-Definite Programming,SDP)方法求得预编码矩阵和相移矩阵的表达式。最后,仿真结果表明,与传统的去蜂窝网络相比,该方案下的网络容量可以显著提高。

溶剂型冷补沥青制备及其黏附性能评价

为制备高性能沥青路面修补材料,研制了9种不同配比的冷补沥青。测量冷补沥青的接触角并通过表面自由能理论计算内聚功、黏附功、剥落功和能量比,结合定量的黏附性测试手段对理论计算的结果进行验证。结果表明,60℃旋转黏度、改进水煮法、光电比色法以及黏结强度测试所得最佳配比与表面自由能计算所得一致,且3种黏附性测试方法所反映的结果无显著差异。冷补沥青最佳配合比为m(沥青)∶m(柴油)∶m(SBS)∶m(增黏树脂)∶m(抗剥落剂)=100∶30∶3∶5∶0.5,可直接采用光电比色法和接触角测试相结合或黏结强度测试与接触角测试相结合的方法量化评价其黏附性。

等离子体处理对于聚丙烯胶粘接强度的影响

聚丙烯(PP)是微流控芯片常用的加工材料,但由于PP表面非极性,表面能低,使得PP材料的微流控芯片胶粘接强度较差,难以满足使用要求。等离子体处理是聚合物表面改性常用的一种方法,系统研究了等离子体处理对于PP胶粘接强度的影响。利用光学接触角测量仪和扫描电子显微镜等对比分析了等离子体处理前后PP表面的接触角、自由能和微观形貌的变化,实验发现等离子体处理后PP表面去离子水的接触角由99°减小到了75°,表面自由能由31 m J/m2增大到了49 m J/m2,PP表面由疏水性变为了亲水性,并且表面出现了大量的纳米级凸起和凹坑,从而揭示了等离子体处理对于提高PP胶粘接强度的机理。对等离子体处理的工艺参数进行了优化,利用T剥离强度试验方法对PP的胶粘接强度进行了测试,PP的平均胶粘接强度提高了24%。

Diffusion behavior of Cr in gradient nanolaminated surface layer on an interstitial-free steel

Nanolaminated structures composed of low-angle grain boundaries(LAGBs) possess high thermal stability. In this paper, a gradient nanolaminated(GNL) surface layer with smooth finish was fabricated on an interstitial-free steel by means of surface mechanical rolling treatment. Microstructural observations demonstrated that the average lamellar thickness is about 80 nm in the topmost surface layer and increases with increasing depth. High thermal stability was confirmed in the GNL surface layer after annealing at 500℃. Diffusion measurements showed that effective diffusivity of Cr in GNL layer is 4–6 orders of magnitude higher than lattice diffusivity within the temperature range from 400 to 500℃. This might be attributed to numerous LAGBs or dislocation structures with a higher energy state in the GNL surface layer. This work demonstrates the possibility to advanced chromizing(or other surface alloying)processes of steels with formation of GNL surface layer, so that a thicker alloyed surface layer with a stable nanostructure is achieved.

悬浮区熔炉线圈后狭缝倾角对电磁场的影响

为提高悬浮区熔(FZ)法的成品率,使用模拟计算软件研究了FZ硅单晶的生长过程。通过Comsol Multiphysics软件模拟了FZ炉线圈产生的电磁场,分析了线圈后狭缝倾角对电磁场的影响。随着线圈后狭缝倾角的增加,线圈台阶处和线圈底面坡面处的后狭缝位置向后狭缝倾斜方向偏移,导致后狭缝下方的磁场强度减弱,熔化的多晶硅表面和熔体自由表面的电磁能量等值线向后狭缝偏转方向偏移。结合熔化的多晶硅表面和熔体自由表面的电磁能量、电磁能量差与线圈后狭缝倾角的关系曲线,发现线圈后狭缝倾角为30°左右时,线圈产生的电磁场更有利于硅单晶生长。