静电雾化场的数字全息实验研究

为了获取静电雾化场中雾滴的空间位置、尺寸和速度信息,利用同轴数字显微全息方法,设计并搭建了雾化场测量装置,横向测量范围Ø12.5mm,空间极限分辨率90.5LP/mm,能够实现直径8μm雾滴的测量。在该装置上,进行了单毛细管和多毛细管在稳定锥-射流模式下雾化场的测量,取得了不同流量下雾滴平均直径和平均速度随流量的变化关系。结果表明,该装置能够在单次测量中同时给出雾滴空间位置、尺寸和速度信息。该研究对于雾化参量的测量以及静电雾化研究有重要意义。     

基于轨迹图像的雾滴颗粒运动速度光电测量方法

为了对双介质喷嘴雾滴颗粒的运动速度分布进行测量,建立了基于波长为532nm连续激光器和工业相机组成的在线测量系统,并获得了雾滴的轨迹图像。采用Steger方法对获得的粒子轨迹图像进行了图像处理,取得了雾滴颗粒的速度分布的数据。结果表明,所开发的基于粒子轨迹图像雾滴速度分布光电测试方法可以满足在线测量的要求。     

同心柱筒中混合排列向列相液晶中的挠曲电效应

本文研究径向电场作用下同心柱筒中混合排列向列相液晶的指向矢分布,重点研究挠曲电效应对指向矢分布的影响。向列相液晶处于同心圆柱构成的薄层间,内表面径向锚定、外表面轴向锚定以及内表面轴向锚定、外表面径向锚定构成两种同心柱筒混合排列模型。基于向列相液晶Frank弹性理论,通过差分迭代方法,分别在强锚定及弱锚定边界条件下,研究了两种模型中挠曲电效应对指向矢分布的影响。研究结果表明:挠曲电效应在薄层内边界、外边界以及薄层内部对指向矢分布有着不同的影响;同心柱筒中指向矢分布由柱对称性、边界锚定作用、介电耦合作用、挠曲电效应的综合作用所决定。     

压缩式雾化器雾滴粒径检测方法研究

雾化器雾滴粒径分布作为评价雾化器性能和治疗效果的重要指标,其检测方法对测量结果起到关键作用.通过采用Mie散射改进算法的激光粒度分析仪,研究压缩式雾化器流量、雾化杯、检测载体、检测环境对雾滴粒径分布的影响,试验表明:在检测环境和条件相同情况下,压缩式雾化器输出流量与雾滴粒径分布及占比呈正相关,与相同雾滴体积分布及占比前...     

基于模式分类的喷嘴料液雾滴速度测量研究

测量烟叶加料过程中料液雾滴喷射后的速度变化,为烟叶加料均匀性的评价提供有效数据。实验从喷嘴的轴向面采集喷出的雾滴图像,对采集到的图像进行预处理和图像分割,采用模式分类对分割出的雾滴分类,根据高速相机成像的测量方法计算出每一类雾滴的速度。研究结果表明,由模式分类统计出的数据,其准确率达到95.65%,使用该数据计算出的速度误差为4.6%,两项数据均在规定范围之内。使用高速摄像机获取图像,采用软件计算出雾滴速度,与早期实验方案相比,降低了测量设备价格,实现低成本测量;模式分类的测量方法准确率较高,为后续加料均匀性分析提供可靠的数据,且效率更高,同时为数据测量的智能化打下基础。     

脑电计算问题应用平台的设计与实现

脑电正及脑电逆问题的研究一直是脑电研究领域的核心。文中针对脑电计算问题进行了算法研究和软件系统设计开发。首先对已有的脑电计算方法进行研究分析,选出适宜的计算方法嵌入到软件系统中;基于Visual C++6.0平台,设计开发了系统软件,脑电正系统可以以灰度图形式直观显示出脑电压大小的分布情况,脑电逆系统可由获取的脑电数据快速地计算出偶极子电偶极矩的大小并实时显示。该系统具有界面友好、操作简单、易于扩展等特点。     

电网络模型的动力系统模拟应用研究

根据相似原理建立了电系统与其他系统的对应原则,进行了动力系统的电方法分析应用研究。在弹簧机械系统的分析中,建立了相应的电网络拓扑结构,实现了该系统的电网络建模及仿真计算。通过对某段选定的血管拓扑结构建立实现了其电网络建模研究分析。根据电网络方法和工程热力学在某些本质方面的一致性,描述了以热力学参数为描述对象的端口网络和’相应模型。说明了电网络模型可以成为能流系统的通用处理工具,在非电系统的分析优化中将有着广泛的应用前景。     

超声雾化频率与雾化粒径关系的实验研究

研究建立了超声雾化装置,使用不同频率的压电换能器对抑尘剂进行了雾化,利用welas 2000气溶胶粒径谱仪对雾化产生的雾滴粒径进行了测定。结果表明,相同雾化条件下,雾滴粒径随压电换能器的振动频率增大而减小,减小量与理论计算具有较好的相合性。     

云雾中飞机尾流毫米波雷达多普勒特性研究

构建了尾流中云雾滴运动微分方程,通过求解运动方程得到了尾流中云雾滴的运动轨迹、速度分布等特性.分析了尾流中云雾滴的密度分布特性,并以典型的W波段雷达为例,分析了云雾中尾流的探测距离.在此基础上,提出了一种云雾中尾流雷达多普勒特性模拟方法,得到了典型毫米波雷达空间分辨率和观测视角下云雾中尾流的多普勒特性.研究结果表明,云雾中尾流毫米波雷达回波调制了丰富的尾流速度场信息,可为航空安全提供特征支撑.     

半导体器件热特性的电学法测量与分析

利用电学法测量器件的温升、热阻及进行瞬态热响应分析是器件热特性分析的有力工具．本文利用电学法测量了ＧａＡｓＭＥＳＦＥＴ在等功率下,加热响应曲线随电压的变化,并通过红外热像仪测量其温度分布,结果表明电学法测得的平均温度与温度分布有很大关系．理论计算也表明了这一点．在等功率条件下,电学平均温度随着温度分布趋于均匀而减少．该方法可用来判断器件的热不均匀性．     

A new cymbal-shaped high power microactuator for nebulizer application

Inhalation therapy is being applied in the home care field to a gradually increasing degree, and therefore two issues of great importance are the convenience and portability of medical devices. Hence, this paper presents a novel cymbal-shaped high power microactuator (CHPM) that includes a ring-type piezoelectric ceramics and a cymbal-shaped micro nozzle plate. The latter can focus energy on the center of the nozzle plate and induce a large force, which provides the cymbal-shaped microactuator with high power to spray medical solutions of high-viscosity produce ultra-fine droplets and increase the atomization rate. In this research, the CHPM can reduce liquids to droplets of an ultra-fine size distribution (Mass Median Aerodynamic Diameter, MMAD), increasing the nebulizing rate and enabling the spraying of high-viscosity fluids (lavender oil, cP > 3.5). The ultra-fine droplets were of a MMAD of less than 4.07 μm at 127.89 kHz and the atomization rate was 0.5 mL/min. The drive voltage of CHPM was only 3 V, and the power consumption only one-tenth that of ultrasonic atomizers at 1.2 W. The simulation and experiments carried out in this study proved that the droplets are much smaller than those produced by current conventional devices. Therefore, the CHPM is suitable for use in the development of a convenient and portable inhalation therapy device.     

高压静电雾化液体的测试研究

在实验的基础上,重点研究了高压静电雾化除尘器中高压雾化现象的产生以及其相关实验测试分析。在高压静电雾化装置形成雾化带电液滴过程中,通过外加高压条件,雾化液滴形成单分散的雾化水分子团簇结构。雾化液滴在外加高压电场作用下在接地极形成微弱电流,并通过使用串联在接地极的二级运放电路,对高压雾化过程中产生的带电粒子的数量进行分析。实验结果表明,该项实验有效提高了湿式高压静电雾化除尘装置起始粒子浓度,进而提高了除尘器的除尘效率,为后续的研究提供了理论基础和有效的实验数据。     

T型微流控芯片中的液滴形成

以水为分散相、硅油为连续相,对高度为30μm、宽度800μm的T型垂直交错结构微通道中油包水型液滴的形成进行了实验研究。通过改变分散相和连续相流量配比,生成了大小可控的nL级液滴。对流量和液滴直径的关系以及流速、压力在液滴形成过程中的变化趋势进行了分析,得到黏性剪切力和界面张力是液滴形成的主要因素。发现流量较大时,两相在主通道内形成层流,并在微通道的台阶突扩处生成两种类型液滴。同时,在台阶突扩处液滴出现三种排列方式:交错双排Z字型、珍珠项链型和单排型液滴排列,并在低流速下出现液滴破碎现象,其发生主要取决于界面张力和流动阻力的影响。     

Effect of process conditions on uniformity of velocity and wear distance of pad and wafer during chemical mechanical planarization

The kinematics of conventional, rotary chemical mechanical planarization (CMP) was analyzed, and its effect on polishing results was assessed. The authors define a novel parameter, ζ, as a “kinematic number,” which includes the effects of wafer size, distance between rotation centers, and rotation ratio between wafer and pad. The analysis result suggests that velocity distribution, direction of friction force, uniformity of velocity distribution, distribution of sliding distance, and uniformity of sliding-distance distribution could be consistently expressed in terms of the kinematic number ζ. These results become more important as the wafer size increases and the requirement of within-wafer nonuniformity is more stringent.     

Power Enhancement of a Small-Orbit Coaxial Cyclotron Autoresonance Maser (CARM) by Employing an External Radial Electrostatic Field

A proposal is presented to enhance the saturation power of a small-orbit coaxial cyclotron autoresonance maser (CARM) by employing an external electrostatic voltage. Nonlinear simulations show possible increase of 22% of the saturation power with high gain of 67 dB for a transverse electric mode at frequency of 140 GHz. Influences of initial parameters on the saturation power are simulated. It is found that due to the use of an external electrostatic field, saturation power of the wave is sensitive to the ratio of the transverse velocity to the axial velocity, as well as to the spread of the transverse velocity. The physical mechanism of the power enhancement may be that the radial force produced by the radial electrostatic field superposes an extra motion on the electron beam and thus causes an extra energy coupling between the electron beam and the radial electric component of the wave.     

Functional Polysaccharide Sutures Prepared by Wet Fusion of Interfacial Polyelectrolyte Complexation Fibers

This study reports polysaccharide‐based fibers that can be utilized as biocompatible functional sutures. Fibers are spontaneously formed by spinning at the interface between two oppositely charged polysaccharide solutions. Unlike the common belief that polysaccharide fibers prepared by electrostatic interactions would exhibit weak mechanical strength, it is demonstrated that fibers spun at the interface between two droplets of positively charged chitosan and negatively charged heparin can exhibit high mechanical strength through spontaneous wet‐state fusion of interfiber strands at a spinning wheel. Dry solidification results in multistranded fibers that were ≈100 µm in diameter with a tensile strength of ≈220 MPa. Post fibrous manipulation yields various morphology with straight or twisted fibers, fabrics, or springs. To demonstrate application of the fiber, it is applied as a medical suture. As heparin has a unique ability to bind adeno‐associated virus (AAV), a therapeutic, biocompatible suture exhibiting localized AAV‐mediated gene delivery function can be prepared. This study shows that multistrand fusion of fibers, formed by weak, electrostatic interactions and followed by drying solidification counterintuitively results in mechanically strong, functional fibers with various potential applications.     

激光手术喷雾冷却中单个液滴蒸发特性

制冷剂喷雾冷却(CSC)是激光治疗鲜红斑痣(PWS)手术的重要辅助手段。为了深入了解制冷剂喷雾特性以提高冷却效率、优化喷嘴设计,利用质量传递数法推导传质方程,通过选取合适的阻力系数经验关联式建立了动量方程,考虑液滴蒸发以及与环境气体的对流换热建立了液滴能量方程,初步建立了单个制冷剂液滴平衡蒸发阶段蒸发冷却理论模型。利用建立的模型模拟悬挂水滴冷冻过程的过冷阶段,并在变物性条件下预测了制冷剂液滴温度随飞行距离的变化,结果与实验对比证明了模型的有效性。有关液滴初始参数对液滴蒸发冷却特性影响的研究结果表明,本模型可以为制冷剂喷雾冷却实际应用于激光治疗鲜红斑痣手术提供有效的分析方法。