液-液界面上折射声束位移的实验验证

对折射波束在液-液界面上的现象进行了数值和实验研究，结果表明：当声束从声阻抗大的介质入射到液-液界面上时，折射声束会存在反向位移现象。     

凹面相控阵聚焦声场在液固界面上的反射和折射

开展了凹面线性相控阵列辐射声场在液固界面上的反射和折射特性研究,利用射线近似方法,得到了凹面相控阵聚焦声场在液固界面上反射和折射后的声场渐近解析表达式,对声波在液固曲面上的反射和折射声场进行了分析和讨论. 利用这个解析表达式,对凹面线性聚焦声场在液固平界面和液固圆柱界面情况下固体中折射纵波和折射横波的相控阵声场进行了分析和讨论,发现凹面线阵声场在液固圆柱界面下比液固平界面具有更好的聚焦效果. 关键词： 凹面阵列 超声相控阵 反射与折射     

核磁共振成像技术在液-固-液界面接触角测量中的应用

介绍了利用核磁共振成像的办法获得一般光学方法难以得到的水-破璃-油界面、水-玻璃-苯界面影像的实验工作,并利用得到的图像拟合了其界面接触角的值.实验中首次将核磁共振断面成像的办法应用到接触角影像分析中去,并且作了从气-固-液接触角测量到液-固-液接触角测量的有益尝试.     

液-液两相液层间传质过程的Rayleigh-Bénard-Marangoni对流特性

传质引发的Rayleigh-Bénard-Marangoni对流(RBM对流)对化工传递过程有着显著影响.但是,已有的相关研究多集中于气-液体系,并且有限的针对液-液体系的相关研究尚缺乏对RBM对流演化及其引发的界面扰动行为的深入分析.因此,本文基于阴影法设计搭建了竖直狭缝内液-液两相液层间传质过程的RBM对流特性可视化实验平台,并实验观测了水-甲苯-丙酮三元体系中丙酮组分扩散传质时出现的RBM对流结构以及其向下层水相主体的发展演变过程,探讨了水相丙酮初始浓度、甲苯相丙酮初始浓度以及甲苯层厚度对RBM对流特性和液-液界面形貌的影响.研究表明:在Rayleigh-Taylor不稳定性作用下,水相上层密度(重力)分层"界面"下凸沉降形成波浪形丘状"界面",并随着"界面"处密度与压力失调的加剧而演变成羽状流;因羽流区"界面"不同浓度梯度引起的传质特性差异,羽状流又可以演变成弱羽状流和强羽状流两种形态;当丙酮浓度梯度增大到一定程度后,近界面处短时间内产生大量RBM对流结构,且结构间相互影响增强而聚并成对流团,并随着传质过程的进行,逐渐演变成独立的强羽状流; RBM对流强度与上下液层丙酮浓度梯度大小呈正相关关系,且液-液界面粗糙度及其非稳态波动随着丙酮浓度梯度的增加而增大.     

油水界面液位的光纤测量技术研究

油品储罐是储存易燃、易爆油料的重要设备,在石油、化工、交通、储运等行业部门应用广泛。油罐液位检测是相关企业生产、管理及安全控制的重要环节。针对轻质油品储运管理及安全监测的需求,提出了一种基于光纤垂直端面反射的检测方法。光纤端面接触油、水表面时形成玻璃-油、玻璃-水反射界面,借助油、水折射率不同的特点,测量光纤中反射光强的变化来测定界面位置,实现对油罐中油水界面的测量,测量精度可达毫米级。     

固-液界面可聚合脂多层膜的Ｘ射线散射研究

报道在北京同步辐射装置上有关固-液界面的研究结果,在漫散射站成功实现了固-液界面的X射线散射测量.将二乙炔酸的异丙醇溶液滴在硅基底表面,溶剂挥发后形成晶态二乙炔酸多层膜.X射线在位观测实验表明,和水长时间接触后,水分子渗透到多层膜亲水界面,样品呈液晶态.在大尺度上分子膜的热起伏符合液晶的线性弹性理论模型,但小尺度上分子的位移主要由缺陷引起.光照聚全后分子膜的弯曲模量变大,缺陷引发的分子位移范围也增大.     

有限入射声束在液固界面声反射的数值研究

采用将有限声束分解为一系列平面波的方法，对液固界面声束的声反射问题进行了数值研究，结果表明，当声束入射角为瑞利疲激角时，反射声速有明显位移；当声束在液固界面“掠射”时，反射声速显著变宽，文中还讨论了束宽对反射声速横截面上声场分布的影响。     

熔石英玻璃材料测试用折射液配制技术研究

为了对熔石英光学玻璃应力及光学均匀性进行测试,提出一种测试用高精度折射液配制方法。根据分子结构定量关系及组分的摩尔折光度定量可加的原理,推导了折射液配比公式并制定了折射液的配比工艺;分析了折射液的折射率随测试温度和测试波长不同的变化规律,并进行了实验验证;最后分析了折射液精度对测试结果的影响。通过上述方法在实验室环境配制出与熔石英折射率匹配精度为±2×10-5的折射液;通过对粗磨光学玻璃透射比实验表明,采用该方法配制的折射液对粗磨光学玻璃在450～700nm光谱范围内透射比从低于20%提高到97%以上;利用该方法和选用的成分配制的折射液具有毒性小、挥发性小、无色无味、长时间保存折射率保持性好的优点,可以很好地用于熔石英光学玻璃材料特性测试。     

液液传质的全息测量

本文介绍了摄制液液传质界面现象全息图的方法以及影响全息图记录质量的因素，为深入研究液液传质界面现象开辟了新途径。     

基于光的反射与折射定律的表述方法推导及应用

光的反射和光的折射是几何光学应用中最基本的方法。在现代精密光学元件加工过程中,其不同的表述方法可以为光线追迹、棱镜误差分析以及棱镜装调提供不同的解决思路。介绍了光的反射定律和折射定律的传统形式表述方法,并推导了光的反射定律和折射定律的矢量、矩阵及四元数3种表述方法。通过Matlab辅助下的模拟计算,得到施密特棱镜检验光路中2个不同区域入射光线的反射在水平方向上对称分布于前表面反射像两侧,与实际应用相符,实现了矢量、矩阵和四元数表述方法在施密特棱镜检验光路中的应用。3种表述方法可以为光线追迹、棱镜误差分析以及棱镜装调提供科学、实用的解决方法。     

New insights into the mechanisms of ultrasonic emulsification in the oil–water system and the role of gas bubbles

Ultrasonic emulsification (USE) assisted by cavitation is an effective method to produce emulsion droplets. However, the role of gas bubbles in the USE process still remains unclear. Hence, in the present paper, high-speed camera observations of bubble evolution and emulsion droplets formation in oil and water were used to capture in real-time the emulsification process, while experiments with different gas concentrations were carried out to investigate the effect of gas bubbles on droplet size. The results show that at the interface of oil and water, gas bubbles with a radius larger than the resonance radius collapse and sink into the water phase, inducing (oil–water) blended liquid jets across bubbles to generate oil-in-water-in-oil (O/W/O) and water-in-oil (W/O) droplets in the oil phase and oil-in-water (O/W) droplets in the water phase, respectively. Gas bubbles with a radius smaller than the resonance radius at the interface always move towards the oil phase, accompanied with the generation of water droplets in the oil phase. In the oil phase, gas bubbles, which can attract bubbles nearby the interface, migrate to the interface of oil and water due to acoustic streaming, and generate numerous droplets. As for the gas bubbles in the water phase, those can break neighboring droplets into numerous finer ones during bubble oscillation. With the increase in gas content, more bubbles undergo chaotic oscillation, leading to smaller and more stable emulsion droplets, which explains the beneficial role of gas bubbles in USE. Violently oscillating microbubbles are, therefore, found to be the governing cavitation regime for emulsification process. These results provide new insights to the mechanisms of gas bubbles in oil–water emulsions, which may be useful towards the optimization of USE process in industry.     

分子动力学模拟方解石和白云石润湿性

利用分子动力学模拟研究油水分子在方解石和白云石表面的吸附,分析体系的平衡构型、相对浓度、径向分布函数和吸附能,研究方解石和白云石的亲水性并对比二者差异.根据油水分子吸附规律分析方解石/白云石-油水体系作用机理.研究表明：白云石-油水体系更易达到热力学稳定状态并且体系更加稳定;方解石和白云石表面均能够优先吸附水分子并在表面形成双层结构的水膜.其中,白云石表面对水分子吸附强度大于方解石;稳定吸附过程分为两步：范德华力、静电力和O（CaCO₃,CaMg（CO₃）₂）-H（H₂O）氢键共同影响下水分子向晶体表面移动并吸附形成紧密吸附层;O（H₂O）-H（H₂O）氢键作用下游离的H₂O向晶体表面靠近形成扩散层.从分子尺度解释方解石/白云石亲水特性,为碳酸盐岩储层润湿性研究奠定理论基础.     

Hybrid HF–DFT modeling of monolayer water adsorption on (001) surface of cubic BaHfO3 and BaZrO3 crystals

First-principles calculations have been used to study the atomic structure, preferred sites and adsorption energies for water adsorption at different terminations of the cubic phase of perovskite-structured BaHfO₃ and BaZrO₃. By considering different initial positions of water molecules, the possibility of water dissociation has been investigated. It is demonstrated that the site selectivity and the form of adsorbed molecule can be affected by the choice of surface unit cell. Dissociative adsorption was found to be favorable for all surfaces in consideration. Hydroxylation of ZrO₂- and HfO₂-terminated surfaces is accomplished by a noticeable reconstruction of the surface structure of cubic phase towards the orthorhombic phase. Calculated atomic charges in bare and hydroxylated surfaces show that BaHfO₃ crystal is slightly more ionic than BaZrO₃.     

Laser-based sensor for a coolant leak detection in a nuclear reactor

Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment, we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D₂O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange reaction between D₂O and H₂O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation monitoring, humidity monitoring and FT-IR spectroscopy.     

水驱油藏中原油极性物质对吸附和润湿性影响的分子模拟

为了研究水驱油藏中原油极性物质的吸附机理及其对油藏表面润湿性的影响,构建以石英为代表的砂岩岩石骨架模型,己烷为代表的非极性物质模型和以甲苯、胶质和沥青质为代表的极性物质模型,运用分子模拟方法研究4种原油组分和水分子在砂岩油藏表面竞争吸附过程和润湿状态。结果表明：水与4种原油组分在石英矿物表面竞争吸附时,原油中的非极性物质会比极性物质更加容易脱附。极性物质会随着时间的变化逐渐吸附在矿物表面,非极性的物质会随着时间变化逐渐远离矿物表面。吸附过程中静电力起吸附作用,范德华力起排斥作用。最后结合润湿性实验结果,从机理上解释了不同原油组成对润湿性的影响,即原油组分中极性物质含量越高,胶质沥青质含量越大,岩石表面油湿性越大,且水驱过程中润湿性向亲水方向变化越难。结论对提升水驱油藏采收率影响因素的认识有重要意义。     

Measuring lateral efficiency of optical traps: The effect of tube length

An optical tweezer setup is made based on a custom-designed inverted microscope, which can work both in finite and infinite tube length microscopy modes. It is shown that the spherical aberration due to the mismatch in the refractive indices of the specimen (water) and the immersion oil as well as the wavelength can be partially compensated by introducing another source for the spherical aberration provided it has the opposite sign. Changing the tube length is shown to be a good candidate for this effect: an improvement of up to a factor of four has been observed in the lateral efficiency of the trap.     

模拟溢油样品激光诱导荧光光谱的偏振特性研究

激光诱导荧光是海洋溢油探测的有效手段之一,但该技术的应用易受自然水体中叶绿素、CDOM等物质荧光信号的干扰。为了寻求排除自然水体荧光干扰的方法,基于532 nm连续激光器搭建了激光诱导偏振荧光实验装置,并针对六种不同密度的模拟溢油样品和自然水体开展了荧光光谱偏振特性研究。实验结果发现,与自然水体的荧光光谱不具有明显的偏振特性不同,所有模拟溢油样品的诱导荧光均具有明显的偏振特性,这一结论说明激光诱导荧光光谱的偏振特性可以作为排除叶绿素、CDOM等物质荧光干扰的依据。实验还发现,溢油样品的荧光偏振性质因样品种类而异。在线偏振光激发下,原油样品荧光偏振度随波长逐渐降低,其中重质原油样品偏振度降低幅度最大,轻质原油样品幅度最小,而柴油样品荧光偏振度没有明显变化;当周期性改变激发光的偏振状态时,所有模拟溢油样品的荧光偏振度随之发生趋势相同的周期性波动,中质样品荧光偏振度波动的幅度低于重质样品,但明显超过轻质样品。这一结果说明,模拟溢油样品诱导荧光偏振度的波长变化特性及对激发光偏振态的响应特性均与样品密度存在一定关联,其偏振特性可以作为辅助油种识别的重要参量。     

Exploring the separate NMR responses from crude oil and water in rock cores

In analysis of transverse relaxation time (T ₂) curves in a Carr-Purcell-Meiboom-Gill (CPMG) experiment in a multicomponent system originating from measurements of oil and water in rock cores, where internal magnetic field gradients broaden the line widths significantly, there is very little direct information to be extracted of the different components contributing to the totalT ₂ relaxation time curve. From the study of rock cores saturated with different amounts of crude oil and water, we show that with an optimised experimental setup it is possible to extract information from the nuclear magnetic resonance response that is not resolved by any other methods. This setup combines pulsed field gradient methods with the CPMG experiment utilizing data from both rock cores and bulk oil and water. Then it becomes feasible to separate the signals from oil and water where the two-dimensional inverse Laplace transform ordinarily seems to fail.     

H2O分子在五边形BCN上的吸附与解离特性研究

基于密度泛函理论的第一性原理计算方法，研究了H₂O分子在五边形BCN上的吸附与解离过程.研究结果表明，五边形BCN结构的B原子是H₂O分子的最稳定的活性吸附位点. H₂O分子在该活性位点极易解离，其初步解离过程为放热反应且分解势垒仅为0.191 eV,并形成稳定的OH/H产物.深入研究发现，H₂O分子初步解离后的五边形BCN表面，可直接分解后续吸附的H₂O分子.该研究结果为五边形BCN对H₂O分子的吸附解离机制提供理论借鉴.     

紫外分光光度法研究膨胀石墨对汽机油的吸附性能

水体油污染是当今迫切需要解决的环境问题之一。本文研究了膨胀石墨对汽机油的吸附性性能。结果表明,膨胀石墨对汽机油具有较大吸附量,清除水中汽机油的效果很好,除油率高达99%以上。