Influence of electroplating conditions on magnetic properties of Fe-36wt.% Ni alloy film

A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe2+ ]/ n [Ni2+ ], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density(BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B S keeps linear. It is observed that the coercive force( Hc) is enhanced with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density and pH. By comparison, when the bath temperature increases, Hc always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases.     

Thermal spraying of biomaterials

Osteoconductive hydroxyapatite coatings for metallic endoprostheses for hip and knee joint replacement provide a state-of-the-art template for enhanced in-growth of bone cells. However, the high temperature of the plasma jet leads to large scale dehydroxylation and decomposition of the starting powder. A model is being developed to explain the formation of chemically and mechanically inhomogeneous porous calcium phosphate coatings deposited by atmospheric plasma spraying onto titanium alloy substrates. In addition the biofunctionality is being discussed of titania bond coats and their influence on the in vivo performance of hydroxyapatite-titania duplex coating systems.     

Bi-based superconductors fabricated in high magnetic fields

The microstructure and superconducting properties of Bi-2223 superconductor fabricated in high magnetic fields were investigated. The results shows that the Bi-2212 grains with their c-axis parallel to the magnetic field were formed after the partial-melting and solidification in 8 T magnetic field, and transformed into the Bi-2223 grains with c-axis alignment during the further sintering process at 840 ℃ without magnetic field. The conversion of Bi-2212 grains to Bi-2223 grains has the heredity in grain alignment. The mixed structures of the Bi-2223 and the Bi-2212 grains with their c-axis parallel to the magnetic field are formed in samples sintered at 850-855 ℃ in 10 T magnetic field. When sintered in 10 T below 845 ℃, a high proportion of Bi-2223 phase is obtained, however no preferred orientation is observed. The Bi-2223 grains with their c-axis parallel to the axial direction of the vertical tube furnace are formed not only on the surface, but also in the center of the sample sintered at 850 ℃ for 120 h in a 15 ℃/cm temperature gradient without magnetic field. Moreover, the samples sintered in the temperature gradient and in a 10 T magnetic field have a stronger c-axis alignment ofbi-2223 phase.     

PID和自适应算法在脉搏仿真器振动控制中的应用

以实现远程脉诊的脉象物理再现为切入点,设计了能够模拟人体脉象的脉搏振动器,并对振动信号的控制模块进行了设计,构建可还原真实脉象的脉搏再现系统,使在远处的医生能够身临其境地感受到患者的实际脉搏,从而进行诊断治疗。简单介绍了脉搏再现系统的硬件设计,主要包括基于DSP的脉搏信号发生器和模拟人体桡动脉寸、关、尺搏动的电磁振动器。运用自敏感的思路,通过粘贴在振动梁上的应变片敏感振动位移,作为振动控制的反馈量。基于理论分析,建立了基于音圈电机的脉搏振动原理样机,设计了PID控制算法和截断数据LMS算法,并对脉搏信号进行了开环和闭环实验,通过实验结果的对比和分析知,截断数据LMS算法对脉搏波的控制要优于PID算法。     

超声电机驱动的锁紧装置锁效果的试验研究

为了评价超声电机驱动的磁悬浮飞轮锁紧装置的锁紧效果,对锁紧装置弹片开展了试验研究.将锁紧弹片简化为悬臂梁模型,通过测试其根部应力,计算出其端部的变形量大小,进而获得弹片沿径向对飞轮转子的锁紧力大小.试验表明:每个弹片沿飞轮径向产生17.06 N的锁紧力,在250 s内完成锁紧.对比超声电机驱动与电磁电机驱动的锁紧装置,锁紧力大小相似.试验证明:超声电机驱动的锁紧装置能代替电磁电机完成锁紧和解锁功能,为超声电机在磁悬浮飞轮系统中的进一步应用提供了可能.     

微型核磁共振传感器实时监测汽轮机油老化状态

汽轮机油被广泛应用于火力发电厂汽轮机的调节系统,随着使用年限的增加,其润滑性能和电气性能会随之下降。针对汽轮机油老化状态缺少简单有效的实时监测手段这一问题,提出用核磁共振技术进行检测,并设计了一种方便实时监测的微型核磁共振传感器。传感器尺寸为30 mm ×30 mm ×36 mm,重107 g,可以浸泡在汽轮机油中对其进行检测。通过对来自两个发电厂的不同使用年限的汽轮机油进行测量实验发现：汽轮机油的核磁共振参数有效横向弛豫时间T2ef与纵向弛豫时间T1随着其使用年限的增加而减小。该传感器制作成本低,尺寸微小,操作方便,使得实时监测汽轮机油的老化状态成为一种可能。     

应用SPRI技术检测指纹上的化学品残留

介绍了表面等离子体共振成像（ SPRI）的原理,应用自行搭建的SPRI系统采集指纹图像,并分析其中的化学物残留。在实验中,测量了粘有TiO2颗粒的指纹和正常状态下的指纹的SPR吸收光谱,并进行比较分析。实验结果表明：指纹图像有较高的分辨率和对比度;通过对指纹图像进行SPR分析,获得其SPR图谱,能显著观察到其共振波长的变化,从而能实现对残留化学品的检测。     

基于隧道磁阻传感器的三维电子罗盘设计

针对现有电子罗盘在地磁场检测时易受到外界磁场干扰而导致测量精度不高的问题,设计了基于隧道磁阻传感器( TMR)的三维电子罗盘并完成样机制作。研究了实际环境中电子罗盘的误差特性,经椭球拟合校正后,采用基于椭圆假设的椭圆拟合方法对误差进行补偿,补偿后其方位角精度可达0.85°,有效降低94.81%的方位角误差。实验结果验证了TMR传感器在电子罗盘应用的可行性。     

基于磁场指纹辅助的手机室内定位系统

针对当前室内无线定位信号强度易受干扰、设备部署维护成本高等缺点,以及手机在室内航位推算过程中定位误差随时间累积的问题,本文提出了基于粒子滤波磁场匹配的室内定位方法。相比于传统的航位推算方法,通过改进步态判断方式,并提出了动态步长估计算法和卡尔曼滤波航向估计算法,有效减少步态误判和定位误差。同时通过结合航位推算位置选择粒子滤波算法中的重采样区域,加快粒子收敛速度。最后,通过仿真分析和实际室内环境测试结果表明,本文提出的定位方法能够有效地减小定位误差,并实现2米的定位精度。     

栅元有效共振积分的CUDA算法设计与实现

核反应堆中需要实时精确地计算堆芯和增殖材料的有效共振积分或群截面来实现反应堆的安全控制。整个计算过程因为涉及大量的积分运算和庞大的核素截面数据,采用常规的计算方法,计算时耗相当大。基于统一计算设备架构(CUDA)平台,利用图形处理器(GPU)的计算能力,对整个计算过程进行并行化分解,多线程同时运算,大幅度提升计算速度,降低时耗。实验结果表明,在GPU上并行计算所得结果与原始数据没有明显差异,且加速效果显著。