微流芯片

介绍了基于电流变液控制的微流芯片的工作原理和制作过程，由于电流变液的粘度随外加电场的增加而增大，且这种改变是可逆的，响应时间也极快（毫秒量级）。利用此特性，作者设计制成了电流变液数值型微流阀。基于此类微流阀，作者制成了一系列微流器件，例如：微流混合装置、微减震器以及微流泵。     

一种稳定性得到改善的电流变液

用ＳｉＯ２／Ｐ（ＭＭＡ－ＭＡＡ）微囊复合颗粒与甲基硅油混合并加入适量的添加剂所制成的流体具有电流变效应; 其稳定性相对于由微米ＳｉＯ２、纳米ＳｉＯ２ 制成的电流变液有较大的改善．     

电流变液泊肃叶流动的分子动力学模拟

用分子动力学模拟方法研究了电流变液泊肃叶流动中颗粒的运动方式,模拟出的速度剖面分为两个区域,靠近电极区域的颗粒表现为呼吸式的跃迁运动形式,称为跃迁区,而在两个电极中间区域则为平稳运动方式,称为柱塞区.此外模拟出了体积流率与相对压力梯度之间的关系.并分析了临界压力梯度和临界电场强度及阻断流动的影响因素 关键词：     

平行板类电容器电容的计算

平行板电容器是一基本电容器,其电容的计算公式为：C=ε0S/d,对于极板不为平面、面积不相等的平行板类电容器电容的计算则较为复杂．本文利用微积分原理,将一个普通电容器看成无限多个微电容器（平行板电容器）的串联,然后,根据电容器串联规律进行积分,最终求出电容器的电容计算公式．此方法是一个求解电容器电容普遍适用的方法,计算结果可以直接被应用．     

颗粒质量导致的电流变液结构演化特征

考虑电流变液颗粒质量的影响及多粒子近程相互作用,利用等效平板电导模型,由分子动力学方法模拟了泊肃叶流动状态下电流变液结构的演化过程特征;设计制作了实验装置,观测了泊肃叶流动行为,并与模拟结果进行比较.研究表明:在外电场作用下,计及颗粒质量效应后,电流变液结构演化中跃迁区速度变化的峰值减小,进入柱塞区状态的时间延长,柱塞区的宽度加大,且颗粒质量越大,效应越显著.实验观测的泊肃叶流动行为与模拟结果基本相符,且观察到极板壁上的颗粒静止不动,证明了“极板壁上颗粒静止不动”这一假设的正确性 关键词： 电流变液 泊肃叶流动 等效平板电导模型 结构演化     

多气隙电阻板室的时间特性研究

一种具有10个气隙的多气隙电阻板室,在欧洲核子研究中心实验束上进行了性能测试.该探测器采用几何上串联和电极上并联的特殊结构,使用国产玻璃(厚度1?.1mm)作为高压电极,有效灵敏面积为200mm×63mm²,并具有2×6读出条.对7GeV/c的π^－粒子,其探测效率大于99%,时间分辨达到45ps.     

电流变离合器内屈服面瞬态特性研究

研究同心圆筒型电流变离合器内流动屈服面的瞬态响应规律。结果表明：在突加电场情况下,电流变液屈服应力公式中的参数β对流动屈服面的动态特性规律有重要影响。初始时刻,屈服面在筒壁生成,在向间隙内移动的过程中;若β>2.0,屈服面总是先产生于内筒外壁,若β<2.0,屈服面总是先产生于外筒内壁。     

DMFC两相流及其对传质影响的研究

采用自制的实验系统对液态进料直接甲醇燃料电池(DMFC)阳极交叉指状流道内的两相况功特性进行了可视化实验研究.自制的DMFC单电池带有透明窗口,采用镀金的不锈钢阴极极板和透明的聚碳酸脂阳极流场板,电解质为Nafion117膜.实验过程中燃料电池的进口总管和出口总管是水平的,进口流道和出口流道是竖直的.实验发现,出口流道中典型的两相流流型是泡状流、而出口总管中的典型流型是弹状流.进口流道中的气弹和气柱导致了阳极传质恶化.     

密封充气型触发管抖动特性

在冲击大电流装置中，为了获得较大的冲击电流，要求主放电回路中的电感尽可能小，除了减小传输线的电感和采用低电感的电容器之外，常常采用多个触发管并联运行以减小电感，为了可靠地并联运行，要求各触发管能够准确地同时击穿，这就要求触发管的抖动特性很好；另外，在时序电路(如快速摄像)中，要求触发管的抖动时间越短越好，为此，对研制的密封充气触发管抖动特性进行了研究。     

压电换能器数字模型软件包

最近美国NTR系统公司(NTR System Inc.,1902 North 34th Street,Seattle,WA 98103,USA)推出了一个压电换能器数字模型软件包,PiezoCAD。这个软件包用传输矩阵法计算换能器的整体特性。用户可以从软件包里的数据库选择压电材料的参数。这个数据库里有陶瓷、晶体、聚合物和复合材料的板、条、棒的大量参数。用户可以规定多层匹配层、多层背衬层和负载的特性。在电端可以规定各种电匹配网络,包括电阻、电容、电感、变压器和同轴电缆的串联、并联及各种组合。用T型网络表示的非理想变压器也包括在     

非线性弹簧阻尼减振装置的探究

将汽车底盘减振装置简化为以非线性弹簧、阻尼器为主的被动阻尼式吸振器．利用Matlab软件对其在简谐力作用下的响应进行定量绘图分析,研究其振幅衰减、缓冲周期以及与由线性弹簧构成的简单模型进行比较,解释了减振装置具体的工作过程以及其中的基本工作原理．     

RESONANCE RESPONSE OF ELECTRORHEOLOGICAL FLUIDS IN VERTICAL OSCILLATION SQUEEZE FLOW

The resonance effect of microcrystalline cellulose/castor oil electrorheological (ER) suspensions was studied in a compressed oscillatory squeeze flow under external electric fields. The resonance frequency first increases linearly with increasing external field, and then shift to high-field plateau. The amplitudes of resonance peak increase sharply with the applied fields in the range of 0.17-1.67 kV/mm. The phase difference of the reduced displacement relative to the excitation force inverses in the case of resonance. A viscoelasticity model of the ER suspensions, which offers both the equivalent stiffness and the viscous damping, should be responsible for the appearance of resonance. The influence of the electric field on the resonance frequency and the resonance hump is consistent qualitatively with the interpretation of our proposed model. Storage modulus G' was presented for the purpose of investigating this influence.     

Control analysis of the tunable phononic crystal with electrorheological material

The elastic band structure of a two-dimensional phononic crystal (PC) with electrorheological (ER) material is investigated and the plane-wave-expansion (PWE) method is adopted to solve the problem in this paper. The ER material is used to act as a tunable elastic composite inserts and its material parameter can be changed by the applied electric fields. Variations of the band gaps for the phononic composite system are also calculated with various electric fields and it is found to have a significant effect on the band gaps of the phononic system with ER material inserts. The band gaps of the smart system can be controlled and the acoustic characteristics of the system are also changed by applied different electric fields.     

RESONANCE RESPONSE OF ELECTRORHEOLOGICAL FLUIDS IN VERTICAL O SCILLATION SQUEEZE FLOW

The resonance effect of microcrystalline cellulose/castor oil electrorheological (ER) suspensions was studied in a compressed oscillatory squeeze flow under external electric fields. The resonance frequency first increases linearly with increasing external field, and then shift to high-field plateau. The amplitudes of resonance peak increase sharply with the applied fields in the range of 0.17-1.67kV/mm. The phase difference of the.reduced displacement relative to the excitation force inverses in the case of resonance. A viscoelasticity model of the ER suspensions, which offers both the equivalent stiffness and the viscous damping, should be responsible for the appearance of resonance. The influence of the electric field on the resonance frequency and the resonance hump is consistent qualitatively with the interpretation of our proposed model. Storage modulus G′ was presented for the purpose of investigating this influence.     

电流变技术中的控制理论及参数优化

针对ER型动力元件,阐述了含ER技术的机械系统控制方程的建立方法,运用控制理论建立了其状态方程。同时,对其进行了一般性分析及参数优化设计。发现电流变动力元件可以很简单地依靠调整工作位置来改善元件的动态性能。ER型流体控制元件属典型阻尼元件。     

Dynamic vibration absorbers for vibration control within a frequency band

The use of dynamic vibration absorbers to control the vibration of a structure in both narrow and broadbands is discussed in this paper. As a benchmark problem, a plate incorporating multiple vibration absorbers is formulated, leading to an analytical solution when the number of absorbers yields one. Using this analytical solution, control mechanisms of the vibration absorber in different frequency bandwidths are studied; the coupling properties due to the introduction of the absorber into the host structure are analyzed; and the control performance of the absorber in different control bandwidths is examined with respect to its damping and location. It is found that the interaction between the plate and the absorber by means of the reaction force from the absorber plays a dominant role in a narrow band control, while in a relatively broadband control the dissipation by the absorber damping governs the control performance. When control bandwidth further enlarges, the optimal locations of the absorbers are not only affected by the targeted mode, but also by the other plate modes. These locations need to be determined after establishing a trade-off between the targeted mode and other modes involved in the coupling. Finally, numerical findings are assessed based on a simply-supported plate and a fair agreement between the predicted and measured results is obtained.     

Adaptive optical properties of ER fluid incorporating composite particles

Electrorheological (ER) fluid is one of the popular materials used in smart materials and structures. The material properties of ER fluid can be changed markedly while an external electric field is imposed on ER fluid domain. In this paper, the optical properties of ER suspensions consisting of composite particles dispersed in silicone oil are investigated. Both dc and ac electric fields are utilized to be imposed on ER fluid. The transmissivity of light through ER fluid under various electric fields is detected and analyzed. It is shown that the transmissivity of light increases with the increasing electric field strength and time. The change of transmissivity is caused by the formation of particle chains. The higher the particle concentration, the faster the change occurs. When an ac electric field is applied, the transmissivity can be affected by the frequency of electric field.     

液体火箭发动机中声腔抑制不稳定燃烧的声学分析

发展了声腔的分析和数值模型,对液体火箭发动机不稳定燃烧的抑制作用进行了评定,通过迭代计算研究了二维流动和温度分布变化对声腔调 谐和稳定性能的影响,对不同的声腔几何尺寸和温度梯度的稳定性计算结果表明,燃烧带有较大开口面积的声腔会更大程度地改变振荡的空间分布,这种改变而且影响了驱动和抑制燃烧的机理,讨论了在声腔设计安排中正确选择声腔的几何尺寸,且比较了不同长度和不同直径声腔的阻尼特性,通过考察声吸收系统的方法来最优化系统的阻尼,得到了可供设计参考的结论。     

Dynamic analysis and optimal design of a passive and an active piezo-electrical dynamic vibration absorber

This paper is concerned with the dynamic analysis and parameter optimization of both passive and active piezo-electrical dynamic vibration absorbers that are strongly coupled with a single degree of freedom vibrating structure. The passive absorber is implemented by using an R_s∥L_s parallel shunt circuit while the active absorber is implemented by feeding back the acceleration of the structure through a second-order lowpass filter. An impedance-mobility approach is used for the electromechanical coupling analysis of both types of absorbers coupled with the structure. Using this approach it is demonstrated that the passive and active absorbers can be made exactly equivalent. A maximally flat frequency response strategy is used to find the optimal damping ratio of the passive absorber while a robust, optimal control theory is used to find that for the active absorber. It is found that the passive optimization strategy corresponds to an optimal, robust feedback control of 2 dB spillover. Simulations and experiments are conducted to support the theoretical findings.     

Interferometric modulation of an atomic beam by an electric field: A phase hologram for atoms

Electric-field-controlled atomic holography has been demonstrated. A binary hologram pattern was encoded in the gaps of regularly spaced parallel stripes of platinum electrodes formed on SiN4 thin film. Each electrode was either grounded or connected to a terminal. The electrode connections were arranged so that an electric field appeared in approximately half the 512 gaps when a finite voltage was applied to the terminal. By controlling this voltage, we could shift, erase, or switch holographically reconstructed two-dimensional images of atoms on a screen.