Zeta-potential Analyses using Micro Electrical Field Flow Fractionation with Fluorescent Nanoparticles

Increasingly growing application of nanoparticles in biotechnology requires fast and accessible tools for their manipulation and for characterization of their colloidal properties. In this work we determine the zeta-potentials for polystyrene nanoparticles using micro electrical field flow fractionation (mu-EFFF) which is an efficient method for sorting of particles by size. The data obtained by mu-EFFF were compared to zeta potentials determined by standard capillary electrophoresis. For proof of concept, we used polystyrene nanoparticles of two different sizes, impregnated with two different fluorescent dyes. Fluorescent emission spectra were used to evaluate the particle separation in both systems. Using the theory of electrophoresis, we estimated the zeta-potentials as a function of size, dielectric permittivity, viscosity and electrophoretic mobility. The results obtained by the mu-EFFF technique were confirmed by the conventional capillary electrophoresis measurements. These results demonstrate the applicability of the mu-EFFF method not only for particle size separation but also as a simple and inexpensive tool for measurements of nanoparticles zeta potentials.     

基于介电泳的电极阵列电场仿真研究

介电泳方法被广泛地应用于微纳颗粒的分离和操纵中,实现介电泳操作的关键是设计满足所需电场分布的电极阵列.针对目前在微电极阵列设计中尚缺乏简单有效的电场解析方法的现状,提出一种基于格林公式的电极阵列电场的解析方法.首先介绍了传统介电泳和行波介电泳的概念和计算模型,分析了介电泳过程与电极上所施加的交变电压的频率和幅度的关系,然后在确立电极电势的边界条件的基础上,采用基于格林公式的电场解析方法,建立了非均匀电场的解析模型,得出不同条件下的电极阵列电场分布的仿真结果,最后利用FEMLAB有限元仿真软件对解析模型进行了对比仿真, 验证了该解析模型的可行性.基于格林公式的电场解析求解方法能够有效地提高电极阵列设计中的针对性以及缩短电极设计的时间.     

FF总线现场设备的开发

介绍了适合不同层次开发者的 ,基金会现场总线 (FF)产品开发的不同方式及开发环节 ,提供了一套实用的产品开发工具 ,并举例说明如何利用其开发基金会现场总线的现场设备     

基于汽车液力变矩器数值仿真研究

研究汽车液力变矩器动力性能优化问题.液力变矩器作为自动变速器的液力传动元件可以实现汽车的自适应性无级变速稳定性控制等.传统的液力变矩器动力系统模型达不到自适应性能要求.为了解决上述问题,根据液力变矩器的实际工作状况,提出了一种新的液力变矩器汽车动力系统建模现代设计方法.可有机结合修正能头损失的束流理论,忽略掉非重要因素,以简化建模复杂程度.在假设的基础上建立流道的三维仿真模型,然后导入到划分计算网格中,进行仿真,结果表明,采用流场数值仿真技术,大大提高了模型的设计精度和设计效率,具有一定的实际应用价值.     

计算机数值仿真在汽车外流场分析方面的应用研究

对汽车外流场的计算机数值仿真的过程和方法进行了探讨，并建立了两种车型的空气动力学模型，通过对两种车型外流场的仿真计算，得到了它们的各种参数，借此对它们的空气动力特性进行了分析，取得了比较满意的结果。     

User Innovation in Techniques: A Case Study Analysis in the Field of Medical Devices

Users are the primary source of new techniques, i.e. systematic activities by which a complex task is accomplished. Even though user‐generated techniques are a pervasive phenomenon which can be observed in many different contexts, existing research on user innovation has focused on product and service innovations. We focus on this important area of user innovation by studying four cases in the field of medical devices to analyse the processes by which users generate and diffuse new techniques as well as the interdependencies between user‐generated techniques and subsequent changes to product use and product innovation. Our findings suggest that user innovation in techniques triggers product innovation by users and manufacturers. Therefore, users' contributions to total innovation output are much higher than previously considered. Additionally, the diffusion of techniques differs significantly from the diffusion of new products. It can only be achieved with the involvement of diffusion agents and their interpersonal interaction and joint performance of the technique with possible adopters. As the diffusion of a technique is often a prerequisite for the diffusion of any related product, companies are forced to re‐think their marketing strategies.     

Y型喉管流场分析及结构优化

Y型喉管主要应用于粮食供料气力输送中,结构参数设计不当容易导致颗粒聚集管底,引起较大的压力损失,因此对喉管内流场的分析和结构参数的优化设计显得尤为重要.利用欧拉双流体模型,借助Fluent软件对Y型喉管内气固两相流进行数值仿真,重点研究颗粒不同入射角对喉管内流场的影响.针对颗粒易于聚集问题,提出增加横板改进方案.通过数值分析,得到压降与入射角之间的关系曲线图以及喉管内改进前后的流场情况.结果表明,颗粒入射角在45°到75°之间更有利于颗粒输送,横板方案能够有效避免颗粒在管道底部聚集.     

导叶可调式液力变矩器的内流场数值分析

研究LB46型导叶可调式液力变矩器和风力机传动系统的匹配特性问题,为实现风电机组的高效传动,需对变矩器流场的稳定性和可靠性进行研究.根据运行工况设定边界条件,采用Fluent软件SST K-ω计算模型和MRF(multiple reference frame)技术,对不同导叶开度的LB46型变矩器进行全流道数值仿真,并与实验数据对比分析.结果表明,仿真数据与实验结果较为吻合,证明提出的方法能够用来分析变矩器的流场运行状况,为变矩器的后续优化设计提供支持.     

A Data Flow Language for Controlling Multiple Interactive Devices

System designers construct a conceptual model ? independent of, and interfacing with, application and device models ?and apply it to the PS300 graphics display system for assembly purposes.     

Physiological Cost and Air Flow Resistance of Respiratory Protective Devices

Using one of three respiratory protective devices or a ‘no mask’ control, five male subjects were tested at grades of 0, 5 and 10 per cent and a constant speed of 3·5 miles per hour for a total of twelve tests per man. Exercise heart rates and recovery oxygen consumption values were recorded. Air flow resistance values were determined in laboratory bench tests. The resistance of the devices did not significantly alter the exercise pulse rates but did significantly increase the recovery oxygen consumption, particularly at the higher work levels. Recovery oxygen consumption values and the air flow resistance figures were positively related at the higher levels of work. It is suggested that the relationship offers further support for the use of laboratory bench tests as an estimator of the added physiological burden imposed on the wearer.     

双叶片直线翼垂直轴风力发电机流场特性分析

针对双叶片直线翼垂直轴风力发电机的流场复杂多变的问题,采用k-ω(SST)湍流模型进行数值模拟,展开了对垂直轴风力发电机流场特性的分析,建立了风速与位置的关系,得到了风速最低位置以及风速恢复区域.研究结果表明,三维CFD仿真所得数据与风洞试验数据虽然有所偏差但对于研究垂直轴风力发电机的流场特性影响较小;通过对垂直于z轴截面和垂直于x轴截面的风速云图分析得出:低风速区域不关于x轴对称,其偏向于y轴负半轴;利用风速值曲线定量得出随着x/R的增大,低风速区的面积逐渐扩散,其值先减小后增大.这为建立垂直轴风力发电厂建立基础.     

模拟集成器件在RF领域中的应用

模拟工艺技术的快速发展推动了模拟器件水平的极大提高,为模拟集成电路提供了巨大的发展空间.近年来,模拟集成电路在通讯领域中的发展最为讯猛,其中基于RF器件和电路的无线应用已发展为半导体制造业中非常重要的应用领域.文章主要针对RF领域,对用于模拟集成电路的CMOS和SiGe器件的发展动态及趋势作了分析.     

某离心压气机转子叶尖流场测试及可视化分析

对壁面动态压力传感器阵列测试技术进行了研究,并将该技术应用于某离心压气机转子叶尖的动态流场测试中,获取了大量的动态流场测试数据。采用锁相技术和线性插值方法对测试数据进行了处理和分析,并采用数据可视化技术将动态数据转化成压力分布云图,从云图中可以清楚看出离心压气机不同工作状态下转子叶尖的压力变化,有助于分析转子叶尖处泄漏流、前缘溢流以及泄漏流和分流叶片前缘的相互作用。转子叶尖流场测试及可视化分析结果可以为压气机性能验证和数值模拟方法的修正提供重要的技术支撑。     

超音速进气道三维流场数值仿真与性能分析

减小冲压增程炮弹特别是进气道的阻力,可以提高炮弹的射程。建立了冲压增程炮弹超音速进气道的物理模型,采用N-S方程,并运用有限体积法对进气道进行了三维流场的数值仿真,得到了超音速进气道的流场结构图及性能参数,有利进行分析。重点研究了攻角对超音速进气道性能的影响。理论计算了进气道的总压恢复系数,并对进气道总压恢复系数的理论计算值与数值模拟值进行比较分析,基本一致。得到的结论为冲压增程炮弹提供了设计有效参考。     

基于CFD的通信机房流场模型建立与分析

介绍了一种利用计算流体动力学技术分析通信机房流场分布的方法,找出合理的气流组织形式以达到节能的目的.对机房三维物理模型进行非结构化网格划分,选用标准的k-ε湍流模型,设定相应的边界条件,针对不同的空调风速工况,利用Fluent软件对机房内的温度场和速度场进行数值模拟与分析,研究得出合理的风速以降低能耗.该方法能够有效地建立通信机房的流场模型,对制定机房节能方案有重要的参考作用.