超磁致伸缩平面扬声器灵敏度的研究

采用模拟法在半消音室环境里对平面扬声器和动圈式扬声器的灵敏度进行测试,在音频范围内按1/3倍频点选择测试点。搭架数字信号采集系统并调节功率放大器以保证扬声器的输入功率恒定1 W,记录离扬声器轴向1 m处声压计的读数。选取力学参数相差较大的玻璃板、五夹板和ABS塑料板为振动薄板,同时每种材质都有大小相同的两种尺寸。测试结果表明:动圈式扬声器在高频区输出响应下降趋势比平面扬声器明显,平面扬声器的高频响应较好,带宽较宽;灵敏度与振动薄板的材质与面积均存在着一定的关系,声速较高的材料灵敏度相对较高,而面积较大的则低频响应相对强。     

电致伸缩效应和磁致伸缩效应原理及应用

随着高新技术的发展,集传感、驱动和控制功能于一体的智能材料的研究,具有十分重要的意义,作为主要研究的智能材料有压电材料、电致伸缩材料、磁致伸缩材料等。本文主要介绍了电致伸缩效应、压电效应、磁致伸缩效应的产生机理和当前在工业及日常生活中的应用,并简单探讨了其发展前景。     

高灵敏度位移传感器测量超磁致伸缩系数

应用高灵敏度位移传感器测量磁致伸缩量.对传感器进行定标,用定标后的位移传感器测量材料在磁场中的磁致伸缩量,测量磁致伸缩量的分辨率优于1 μm,测量结果准确度较高,样品更换方便,且输出量为电量,便于计算机实时监测.     

无取向硅钢片磁致伸缩特性的实验研究

采用磁致伸缩测试仪测量无取向硅钢片50WW800的磁致伸缩系数,并对不同钢种及不同退火工艺的无取向硅钢片的磁致伸缩系数进行比较,发现磁致伸缩系数存在最大值,且与磁感的大小、退火时间的长短及试样方向等因素密切相关。     

磁致伸缩系数实验测定方法的比较

介绍了测定磁致伸缩的四种测量方法,给出了原理图,并对各种测量方法作了简要分析评价。     

超磁致伸缩驱动电源的设计与制作

用超磁致伸缩材料做成的换能器具有输出力大、响应速度快的特点,这就要求其驱动电源瞬间能输出较大的电流以形成强磁场.由于该换能器是处于间歇工作状态,利用电容的储能原理制成的驱动电源能满足要求,其关键的难点是储能电容的容量要与换能器线圈的参数相匹配,才能得到良好的效果.可用Matlab软件,通过计算机辅助分析的方法确定储能电容的参数值.储能电容的充放电转换开关可用继电器或场效应管实现.实验表明,该电源可用小型的充电电池供电,并具有连续工作时间长,工作可靠,瞬间输出功率大,体积小、重量轻的特点,特别适合野外使用.     

基于超磁致伸缩材料的非圆曲面形活塞销孔加工新型机构

To bear more loads for heavy truck pistons, the shape of heavy truck piston pinhole is often designed as noncylinder form. Current methods cannot meet the needs for precision machining on non-cylinder piston pinhole （NCPPH）. A novel mechanism based on giant magnetostrictive materials （GMM） is presented. New models are established for the servo mechanism, GMM, and magnetizing force of the control solenoid to characterize the relationship between the control current of the solenoid and the displacement of the giant magnetostrictive actuator （GMA）. Experiments show that the novel mechanism can meet the needs to perform fine machining on NCPPH effectively.     

超磁致伸缩作动器的磁路设计

论述了超磁致伸缩作动器的基本原理,根据三种偏置磁场优缺点,选用增加单独线圈产生偏置磁场。在磁路分析的基础上,采用有限元仿真的方法,分析了不同参数和结构对各个组成部分的磁场影响。     

Application of gram-schmidt regression to modeling of giant magnetostrictive material

A giant magnetostrictive material (GMM) model is developed based on the hysteretic nonlinear theory. The Gram-Schmidt regression method is introduced to determine the parameters of the model as well as the relation- ship between the material strain and the strength and frequency of magnetic field in the model. Through comparison, it is shown that this regression method has good performance in significance test. Then the model is applied to study the motion law of a circular plate in classical GMM transducer, which helps control the transducer rapidly and accurately.     

Systematic studies on scan and driving model for flat panel display

Aiming at the time redundancy in the flat panel display (FPD) imaging process, the paper studied some problems for FPD gray scale controlling based on the fractal theory, dissertates the construction of the space-time mapping topology architecture, the proposition of optimal scanning structure for FPD’s gray imaging, and the creation of the fractal theoretic model. Then the logic implementation and system application are presented based on the fractal model of the optimal scan architecture, and the application results achieved target of eliminating time redundancy and increasing the scanning availability. The novel control mode that the fractal scanning IP core described with Verilog language embedded in the FPGA hardware frame can efficiently increase the imaging gray scales and quality in the FPDs scanning controller and speed up the frame frequency of display system.     

Multi-physics coupling field finite element analysis on giant magnetostrictive materials smart component

This study presents a new method to solve the difficult problem of precise machining a non-cylinder pinhole of a piston using embedded giant magnetostrictive material （GMM） in the component. We propose the finite element model of GMM smart component in electric, magnetic, and mechanical fields by step computation to optimize the design of GMM smart component. The proposed model is implemented by using COMSOL multi-physics V3.2a. The effects of the smart component on the deformation and the system resonance frequencies are studied. The results calculated by the model are in excellent agreement （relative errors are below 10%） with the experimental values.     

串行同步双缓冲扫描提高平板显示器的显示亮度和传送利用率

This paper presents a serial synchronous scanning mode in flat panel display (FPD) by adding a latch buffer between the serializer and the driving buffer. Comparing with conventional techniques, the proposed structure can efficiently reduce the brightness loss and improve the transmission performance. Theoretical analysis and experimental results show that the ratio between the lightest weight display time and the relative transmission time is a tradeoff between brightness loss and transmission efficiency.     

超磁致伸缩器的热补偿研究

超磁致伸缩材料的热效应严重影响其控制精度.文章分析了超磁致伸缩器系统的热源,采用试验的方法确定了一定条件下的热应变和磁应变;设计了适合超磁致伸缩器的冷却子系统;基于热应变和磁应变试验曲线提出了软件向上补偿方法.     

圆波导中探针互阻抗特性的研究

应用矢量位函数、反应的概念和互易原理，推导出圆波导中双探针的互阻抗表达式，圆波导是半无限长的，终端接有一定反射系数的负载．发现了探针的互电阻是由主模产生的，而互电抗则是由主模和高次模共同引起的；由于高次模随着探针之间距离的增加急剧衰减，所以对互电抗的主要贡献来自于主模．然而当探针之间的距离趋近于零时，高次模起主导作用，产生很大值的互电抗．互阻抗取决于探针的位置、高度和相互之间的距离，以及终端面的位置．     

Acoustic impedance characteristics of linear compressors

The acoustic field of a linear compressor serves to deliver the compression work to the load, such as the connected cold head of a cryocooler; it plays an equivalently important role as the electrical and mechanical parts, especially in the impedance match issue. This paper studies the acoustic impedance characteristics of a linear compressor. The parameters including the current, the piston displacement, the pressure amplitude, the electrical power dissipation, the power factor, the pressure-volumetric (PV) power delivered, and the efficiency are theoretically and experimentally investigated. Different from previous theoretical studies, optimization for the operations away from the resonance is also included. More general optimization results imply relevance between thermoacoustic engines and linear compressors. The predicted results are validated by the experiments performed on a linear compressor with an adjustable resistive-capacitive (RC) acoustic load. The comparisons between the calculations and the measurements are presented and analyzed. The results provide deeper insight into the mechanism of the linear compressor and the impedance match in a cryocooler system.     

Systematic studies on scan and driving model for fiat panel display

Aiming at the time redundancy in the flat panel display (FPD) imaging process,the paper studied some problems for FPD gray scale controlling based on the fractal theory,dissertates the construction of the space-time mapping topology architecture,the proposition of optimal scanning structure for FPD's gray imaging,and the creation of the fractal theoretic model. Then the logic implementation and system application are presented based on the fractal model of the optimal scan architecture,and the application results achieved target of eliminating time redundancy and increasing the scanning availability.The novel control mode that the fractai scanning IP core described with Verilog language embedded in the FPGA hardware frame can efficiently increase the imaging gray scales and quality in the FPDs scanning controller and speed up the frame frequency of display system.