Three-dimensional direct imaging of structural relaxation near the colloidal glass transition

Confocal microscopy was used to directly observe three-dimensional dynamics of particles in colloidal supercooled fluids and colloidal glasses. The fastest particles moved cooperatively; connected clusters of these mobile particles could be identified; and the cluster size distribution, structure, and dynamics were investigated. The characteristic cluster size grew markedly in the supercooled fluid as the glass transition was approached, in agreement with computer simulations; at the glass transition, however, there was a sudden drop in their size. The clusters of fast-moving particles were largest near the alpha-relaxation time scale for supercooled colloidal fluids, but were also present, albeit with a markedly different nature, at shorter beta-relaxation time scales, in both supercooled fluid and glass colloidal phases.     

Field-Induced Layering of Colloidal Crystals

An electrohydrodynamic methodology has been developed that makes possible the precise assembly of two- and three-dimensional colloidal crystals on electrode surfaces. Electrophoretically deposited colloidal particles were observed to move toward one another over very large distances (greater than five particle diameters) to form two-dimensional colloidal crystals for both micrometer- and nanometer-size particles. This coalescence of particles with the same charge is opposite to what is expected from electrostatic considerations and appears to result from electrohydrodynamic fluid flow arising from an ionic current flowing through the solution. The ability to modulate this "lateral attraction" between particles, by adjusting field strength or frequency, facilitates the reversible formation of two-dimensional fluid and crystalline colloidal states on the electrode surface. Further manipulation allows controlled structures to be assembled.     

采用调节阀系统控制管道的水击

介绍了我国几条输油管道水击试验的基本情况，对管道调节阀系统的功能作了一般性叙述，对水击控制试验进行了详细的分析。强调调节阀系统在水击控制中必须反应灵敏、关阀速度快。指出调节阀的另一重要作用就是启泵保护。启泵和停泵一样，会产生一个水击波，启泵过程也是一个很强的水击控制过程，而调节阀就位于波源处进行控制。在密闭输油中，调节灵敏、动作可靠稳定的调节系统是优化运行和安全运行的根本保障，它的调节速度与压力变     

长距离油,气,水管道混输系统

在海洋油田的开发中，若在海上建立多个开采处理平台，来处理井液（含油、气、水）是极不经济的，于是提出了多相流的管道输送问题，即将末处理的井液输送到岸上，然后进行处理。国外多相流管道混输技术成功地应用于海洋油田的开发，这项技术也可引入荒漠油田及滩涂油田的开发。     

长输管道电气系统与输油站自动化

长输管道实验自动化，电气系统是重要环节，合理设计输油站的电气系统，正确选择与输油站密切相关的电气设备，是保证自动化管线安全平稳输油的基础因素之一。为了配合输油管道自动化，根据输油站电气系统的技术要求，结构我国自动化输油管道电气设计工作的实践，对输油站电气系统与ＳＣＡＤＡ系统间的联系及相应的各类接口作了较详细的介绍，还对变配电设备及泵、阀等关键输油设备的自动化接口置给出出必要的例图，可供从事输油站电     

Monolithic microfabricated valves and pumps by multilayer soft lithography

Soft lithography is an alternative to silicon-based micromachining that uses replica molding of nontraditional elastomeric materials to fabricate stamps and microfluidic channels. We describe here an extension to the soft lithography paradigm, multilayer soft lithography, with which devices consisting of multiple layers may be fabricated from soft materials. We used this technique to build active microfluidic systems containing on-off valves, switching valves, and pumps entirely out of elastomer. The softness of these materials allows the device areas to be reduced by more than two orders of magnitude compared with silicon-based devices. The other advantages of soft lithography, such as rapid prototyping, ease of fabrication, and biocompatibility, are retained.     

基于单片机的液位控制与报警系统的设计

对基于AT89C2051型单片机的液位控制和报警系统的组成与工作原理作了介绍,其具有液位上下极限位置报警、泵和阀门的自动控制、紧急停止等功能,整体可靠实用。     

管道水击增压速率控制技术研究

控制管道水击增压速率对长输管道可防止早选超压，减少泵站压力保护系统的投用；对工艺管道可减轻振动，防止低压仪表与设备损坏。综述了国内外控制管道水击增压速率所采用的措施和装置，主要有泄压阀系统，气压缓冲罐系统，电子－液力泄放系统，橡胶套泄放阀系统，飞轮系统等。着重介绍新型双功泄压阀的原理和结构。在水击增压控制理论指导下，通过对增压速率调节系统数学物理模型的研究，发现在固定阻力下调节的非线性本质，它要求     

石油胶体性质的研究进展

针对石油工业发展进程中原油品质变差、沥青质易于絮凝析出,进而影响原油开采、储运和加工等生产过程的问题,从石油胶体模型、胶体稳定性和胶粒尺寸等方面概述了国内外有关石油胶体性质的研究成果。自石油胶体学说诞生以来,不但得到了小角X射线散射和小角中子散射等实验结果的验证,而且相继建立了不同分散相和分散介质的胶体模型;胶体稳定性的表征方法主要有滴扩散法、光学仪器法、声共振法、粘度法、电导率法;影响石油中沥青质稳定存在的主要因素包括:胶质的含量、形状和尺寸,沥青质的数量和化学结构,添加剂的化学结构;测定沥青质胶粒尺寸的方法主要有3类:散射法、流体力学参数法、光电显微分析法。添加适宜的化学剂能够缓解沥青质的絮凝沉积,提高石油资源的利用率。     

南输成品油管道顺序输送混油问题

对实际运行的南输成品油管道中油品切换操作数据进行分析,发现每次油品切换后混油量及混油长度不完全相同,分析了油品切换、流态变化、管路特征、机泵匹配等因素对顺序输送混油的影响,指出输量小、流速低、混油界面运行时间长是南输成品油管道混油量偏大的主要原因。     

Surfactant-mediated two-dimensional crystallization of colloidal crystals

Colloidal particles can form unexpected two-dimensional ordered colloidal crystals when they interact with surfactants of the opposite charge. Coulomb interactions lead to self-limited adsorption of the particles on the surface of vesicles formed by the surfactants. The adsorbed particles form ordered but fluid rafts on the vesicle surfaces, and these ultimately form robust two-dimensional crystals. This use of attractive Coulomb interaction between colloidal particles and surfactant structures offers a potential new route to self-assembly of ordered colloidal structures.     

Dense packing and symmetry in small clusters of microspheres

When small numbers of colloidal microspheres are attached to the surfaces of liquid emulsion droplets, removing fluid from the droplets leads to packings of spheres that minimize the second moment of the mass distribution. The structures of the packings range from sphere doublets, triangles, and tetrahedra to exotic polyhedra not found in infinite lattice packings, molecules, or minimum-potential energy clusters. The emulsion system presents a route to produce new colloidal structures and a means to study how different physical constraints affect symmetry in small parcels of matter.     

Novel Colloidal Interactions in Anisotropic Fluids

Small water droplets dispersed in a nematic liquid crystal exhibit a novel class of colloidal interactions, arising from the orientational elastic energy of the anisotropic host fluid. These interactions include a short-range repulsion and a long-range dipolar attraction, and they lead to the formation of anisotropic chainlike structures by the colloidal particles. The repulsive interaction can lead to novel mechanisms for colloid stabilization.     

LNG接收站高压泵增加叶轮后的性能变化及影响

随着中国天然气需求量的爆发式增长,LNG接收站外输管道里程不断增长,出站压力随之持续增高,对压缩机、高压泵等设备性能提出了更高要求。以青岛LNG接收站为例,针对外输压力的变化,提出对其4台高压泵增加4级叶轮的改造方法,并对改造后外输高压泵的性能变化及其对LNG接收站工艺运行的影响进行研究。通过对改造后的高压泵扬程、轴功率、效率随着流量增加的变化趋势进行现场测试,结果表明:高压泵增加叶轮后,其扬程、轴功率、效率、电流均显著提高,其中3台高压泵的运行参数可满足LNG接收站现场实际需要,另外1台即使在相同的测试条件下出口压力仍明显偏低;气化器、HIPPS(High Integrity Pressure Protective System)系统、外输管道高报压力及联锁值均需随之上调,接收站高压区连接法兰出现了多处泄漏,应加大巡检频率和力度;当LNG接收站高压泵性能不同时,在运行过程中应该尽量选用性能相近的泵。研究结果可为高压泵的国产化设计、制造提供参考。     

小型液压挖掘机单杆操作系统的研究

针对小型液压挖掘机复杂的操作系统,从人机工程学的角度出发,设计了小型液压挖掘机单杆操作系统.该设计采用传感器采集控制所需信息,配以电液控制阀和单片机控制,利用单杆操作方式简便省力地完成挖掘工作.     

克乌成品油管道复线泵机组的优化运行方案

根据克乌成品油管道复线泵机组输油的原设计方案,当实际年输量低于195×104t/a时,全年间歇性停产时间合计为158d,增大了首站启停输作业次数和设备操作过程中发生事故的概率,并因需要控制首站出站调节阀开度节流而导致能量损失。基于近两年的输油工况,从能耗的角度出发,分析比较了分别运用临时投产与设计安装的泵机组能耗差异,据此提出在不同年输量范围内的泵机组优化运行方案:当年输量为195×104～300×104t时,以新建泵机组"2台给油泵+2台输油主泵(半扬程泵和全扬程泵各1台)"的工况满负荷运行;当年输量小于195×104t,运行临时投产输油泵机组当年输量为300×104～400×104t时,采用新建泵机组"3台给油泵+2台多级输油主泵"的工况满负荷运行;当年输量超过400×104t时,以新建泵机组"3台给油泵+2台多级输油主泵+1台单级输油主泵"的工况满负荷运行。     

成品油管道优化运行方法研究

在管道输送成品油过程中,流量随时间而变,某时刻管道的输量将由各站间供能（开泵方案）,耗能（沿程阻力）及高程来决定,随着混油段的移动,管内输量必然会发生变化,长输管道是在泵机组某种组合方式下运行,在一段时间内,管道全线存在有一个最优泵组合及其运行参数。通过对成品油管道运行系统的分析,建立了成品油管道的优化运行数学模型和求解方法,通过对成品油管道系统的运行方式,设备组合及工艺参数的优选,确定能耗最低的运行工况,达到成品油管道优化运行的目的。     

输气管道线路截断阀布置中的改进

在输气管道设计中,如果按地区等级设置截断阀之后再加设大型河流两侧的岸边截断阀,截断阀的数量将大大增加。通过分析截断阀的作用,提出了恰当而合理的布置方案,减少了截断阀的数量,并在广东LNG工程中得到了成功的应用。     

LIQUID CRYSTALS: New Banana Phases

Liquid crystals-materials that flow like a fluid but are optically anisotropic like a crystal-exhibit large responses to modest external disturbances. In his Perspective, Lubensky discusses the advances reported in two papers in this issue, both of which involve liquid crystals made from V-shaped or bent-core molecules. Walba et al. report a synthetic strategy for producing a ferroelectric phase from achiral bent-core molecules. Pratibha et al. show that new liquid crystalline phases form when bent-core molecules are mixed with a particular class of rodlike molecules. These papers introduce new molecular designs that yield new liquid crystalline phases with controlled structure and properties.     

国内外输油泵的结构特点和维护要点

在对中比转数梯森泵、宾汉姆泵、国产输油泵的结构特点及运行维护分析以比的基础好各种输油泵的外形构造、叶轮、口环、涡室、机械密封室，轴承及轴在润滑系统等主要部件。从泵的特性参数来看，其综合技术指标都比较先进，特别是梯森泵和宾汉姆泵，目前在国内外工输管道中起到了艇，进口泵构合理，性能优良、运行效率高、维修方便、但存在着人格昂贵、购入手续繁琐等问题。