向下鼓气泡进入水或磁性液体的数值模拟与实验验证

应用数值与实验的方法分析了气泡向下鼓入水和磁性液体的过程,通过数学模型应用PLIC-VOF方法仿真重现了气泡的形成与破裂机理,通过数值模拟获得了气泡的形状与生长周期,用CCD摄像头完成实验测量,实验与模拟达到了数值上的吻合。     

磁性液体-硅油两层流动界面的数学模拟

采用二维笛卡儿坐标系,数值求解了磁性液体和非磁性液体体系的连续性方程、双动量方程、运动方程以及磁势方程,模拟了磁性液体-硅油的两层流动。其中自由边界采用PLIC VOF方法跟踪．表面张力采用CSF方法模拟。通过对方程的数值求解,研究了外加磁场强度、进口速度分布、初始表面扰动对界面形状和界面张力的影响。     

气泡的生成和多种流体的模拟

为模拟生活中常见的流体现象,提出一种基于物理原理的气泡生成算法,并将应用于2种不可相溶流体模拟问题的VOF(volume of fluid)方法推广到任意多种不可相溶的流体模拟问题.在气泡生成算法中,通过调整模拟区域速度场的散度值,来模拟在气泡生成过程中由于液体和气体之间的状态转变导致的流体体积膨胀.在扩展的VOF方法中,使用物理学中的Skin-Onion方法将描述不同流体界面的多个VOF组合在一起,从而正确地描述任意多种流体问题.气泡生成和多种流体模拟的实验结果表明,采用文中方法可取得较好的视觉效果.     

磁性液体的传感特性及原理应用研究

该文介绍了磁性液体应用在传感领域的独特性能,分析了磁性液体在传感器方面的各种应用研究.利用磁性液体的电磁响应和粘度等特性可开发出各种新型传感器.分析了各种磁性液体新型传感器的工作机理和应用方向,并对其应用前景进行了分析展望,指出其中有待研究的方向和意义.     

一种磁性液体加速度传感器模型的参数辨识方法

针对磁性液体加速度传感器模型的参数辨识问题,提出一种改进混沌粒子群算法。该算法利用改进的logistic映射对粒子群进行混沌初始化,并采用抛物线规律对迭代过程中的惯性权重进行实时调节。算法最终辨识出了传感器中磁芯吸附磁性液体后的等效长度、等效半径及等效相对磁导率。实验结果表明,该方法辨识出的参数相对误差小于0.85％,且辨识曲线与参考曲线的拟合度在94.37％以上。     

舰船尾流中气泡的结构静力分析

舰船尾流具有独特的声学特性,气泡是产生其声学特性的主要原因.气泡对入射声波的散射/反射作用与谐振频率有关,表现在声波压力作用下气泡的变形和表面位移随声波频率的变化.为分析尾流中气泡的主动声学特性,建立尾流中气泡的主动声特性模型,计算气泡属性材料参数,建立尾流中单气泡的有限元结构模型,分析气泡在结构静力作用下的变形,可得出模型表面节点位移变化与载荷频率之间的关系,为有限元方法在分析舰船尾流中气泡声学特性的可行性提供了依据.     

高职学生起始信息能力的调查与分析

该文针对高职新生入校时的起始信息能力水平进行了深入调查,并在此基础上探讨了如何培养高职学生的信息能力,旨在推进高职院校的信息素养建设。     

Y型微管道中磁性纳米液体对混合率的影响

利用流动显示手段观测了Y型微管道内含纳米磁性颗粒的液体与去离子水的混合.研究了在Re=0.5～4,磁性颗粒体积分数0.38%-1.54%时,外加静磁场(场强40 Gs)对液体混合地影响.证实了磁场作用可以使完全混合长度大大缩短.同时初步分析了Re和体积分数Ψ对混合长度的影响.     

一种磁性收信天线的设计与分析

文章设计了一种垂直极化磁性收信天线,详细论述了该天线的设计方法,并给出了天线系统的方向图。     

磁性纳米材料的制备及在生物传感中的应用

磁性纳米材料是一类具有特殊性质的纳米材料,其制备方法和在生物传感中的应用受到广泛关注。该文综述了磁性纳米材料的制备方法以及其在生物传感领域的应用。介绍了常见的磁性纳米材料制备方法,包括化学共沉淀法、热分解法和水热法等。探讨了磁性纳米材料在生物传感中的应用,为生物传感技术带来了新的可能性,并且探讨了其不足与未来的改进方法。     

双梁磁力压电振动能量采集器的实验和仿真

基于非线性技术改善能量采集器的能量采集效果作用,本文研究了非线性磁力耦合的双悬臂梁压电振动能量采集器,该采集器由两条不同的固有频率悬臂梁与永磁体组成.本文给出双梁磁力耦合压电能量采集器模型并建立了动力学方程式,通过实验测试获取相关参数与拟合磁力公式,数值仿真分析了双梁固有频率比1∶1.2与1∶1.5和永磁体初始间距40mm与30mm的4种结构能量采集器的电压输出性能与频率特征.根据数值分析设计实验:外激励加速度3m/s2作用下,双梁磁力结构能量采集器比单梁线性结构多一个电压共振峰;双梁固有频率比为1∶1.5比双梁固有频率比1∶1.2的电压响应带宽宽;初始磁距30mm共振峰值分别为(12Hz,39.4V)与(18Hz,13.4V)比初始磁距40mm两电压共振峰高且电压共振峰峰之间的电压输出比其他组合结构高.     

磁流变抛光液磁性颗粒体积分数在线检测装置研制

分析了互感法检测磁流变抛光液中磁性颗粒体积分数的基本原理,并研制出相应的原型装置。该方法的测量输出电压与抛光液磁性颗粒体积分数呈线性关系,磁性颗粒体积分数变化1%时输出电压变化约23.4 mV,测量结果与抛光液流量大小无关。可以实现对常用磁流变抛光液中磁性颗粒体积分数的在线检测,为实现磁流变抛光过程中抛光液成分的稳定控制提供测量基础。     

Peristaltic flow of a Sisko fluid in an endoscope: analytical and numerical solutions

This article deals with the peristaltic flow of a Sisko fluid in an endoscope. The inner tube of the endoscope is fixed, while outer tube is flexible. Continuity and momentum equations are utilized in the mathematical analysis and obtained both the analytical and numerical solutions. The analytical solution has been found by the homotopy analysis method and the numerical solutions are carried out by the shooting technique. The comparison of both the solutions are presented. And the quantitative behaviours of the solutions are discussed.     

Electric and magnetic fields in photoalignment of liquid crystals

The results of investigation of slow surface dynamics (easy axis gliding), induced by secondary illumination of photoaligned substrates with linearly polarized UV or blue light in the presence of electric (magnetic) fields, are presented for the first time. The initial surface orientation of nematic liquid crystal (NLC) was provided, in accordance with the standard photoalignment technique, via preliminary UV treatment of the glass substrates coated by sulfonic azo‐dye SD1 film. The experiments fulfilled for the two geometries, A and B, corresponding to the normal (A) and parallel (B) orientation of fields relatively to liquid crystal (LC) layer, revealed different effects induced by electric (magnetic) fields. For geometry A, strong electric field applied, in combination with a linearly polarized blue light, to the planar layer in a sandwich‐like LC cell with two photoaligned substrates results in simultaneous reorientation of easy axis on both substrates. It demonstrates the possibility of an azimuthal rotation of monodomain planar samples of LCs. For geometry B, usage of “in‐plane” electric (magnetic) fields in the cell, composed of photoaligned and rubbed substrates, speeds up reorientation process of NLC easy axis respectively to pure light‐induced reorientation. It provides electric control of operating times in previously proposed optical rewritable technology.     

Application of artificial neural network and fuzzy logic in a case-based system for initial process parameter setting of injection molding

Determination of initial process meters for injection molding is a highly skilled job and based on skilled operators know-how and intuitive sense acquired through long-term experience rather than a theoretical and analytical approach. Facing with the global competition, the current trial-and-error practice becomes inadequate. In this paper, application of artificial neural network and fuzzy logic in a case-based system for initial process meter setting of injection molding is described. Artificial neural network was introduced in the case adaptation while fuzzy logic was employed in the case indexing and similarity analysis. A computer-aided system for the determination of initial process meter setting for injection molding based on the proposed techniques was developed and validated in a simulation environment. The preliminary validation tests of the system have indicated that the system can determine a set of initial process meters for injection molding quickly without relying on experienced molding personnel, from which good quality molded parts can be produced.     

玉米不同品种接种MDMV后叶片内过氧化物酶及其同工酶的变化

对4个感病程度不同的玉米品种接种玉米矮化花叶病毒（MDMV）7d后植株叶片内过氧化物酶（PO）活性经研究表明：玉米接种病毒后PO活性均有提高,但提高幅度不同且酶活变化波形差异大。抗病品种接毒前酶活低且波形变化平稳,接毒后第2天酶活急剧增高且波形变化大,而感病品种接毒后酶活变化不大且波形一致。玉米PO同工酶酶谱简单,与对照比较,接毒后抗、感品种带纹数目变化不大,但带纹浓重而重叠。抗病品种接毒后第2天带纹突然加重,且持续增加,而感病品种有持续减弱趋势。     

Experimental and simulation analysis of a WiMAX system in an emergency marine scenario

The paper presents several experimental and simulation activities aimed at providing a proof-of-concept for a marine emergency network in which the main components are a WiMAX system and a satellite link. WiMAX represents quite a novelty for the marine environment and its integration with the satellite link turns out to be remarkably efficient and greatly contributes in improving the utility and usability of the emergency network. These concepts are proved through a series of tests and analysis. Firstly, we report an experimental analysis of the coverage range of the WiMAX system in the marine environment in terms of both RSSI and throughput. Then, we discuss the feasibility and performance of a joint WiMAX-satellite path (in terms of throughput and perceived quality of VoIP calls), and report an experimental study that verifies the robustness of the WiMAX links under the interference of typical marine equipments such as radars. Finally, we present a simulation study targeted at evaluating the maximal capacity of the system in terms of VoIP calls under different WiMAX system configurations.     

修正的优化无偏GM(1,1)模型在瓦斯事故预测中的应用

针对无偏GM(1,1)模型可能因个别异常点导致预测误差很大甚至失效的问题,建立了修正的优化无偏GM(1,1)模型。该模型剔除了异常点,并用一次插值法得到的新数据代替异常点,最后对拟合、预测值作残差修正。将该模型用于煤矿瓦斯事故遇难人数预测,结果表明,修正的优化无偏GM(1,1)模型大幅提高了煤矿瓦斯事故遇难人数的拟合及预测精度,后验差精度检验等级为好,其预测值的相对误差绝对值为0.070 4,仅为优化前的40.8%。