磁带的磁性测量

引言磁记录介质的磁性测量对于科研和生产都是十分重要的。对于磁带和软盘的磁性测量,现代常用振动样品磁强计(VSM)和φ-H描迹仪,对于硬盘的磁性测量所需样品一般是破坏性的,IBM公司采用TCM(转移曲线测试仪)可以非破坏性地测量硬盘的定向系数α(或OR)。磁记录介质的磁性参数有:剩磁Br,矫顽力Hci,矩形比S,半峰宽度ΔH和定向系数OR。     

磁记录介质晶粒磁相互作用参数ΔM及其测量方法

对于磁记录介质,记录噪声与晶粒间磁相互作用相关.ΔM是表征磁记录介质晶粒间磁相互作用的重要参数.首先介绍了它的理论依据和意义,接着阐述了通过振动样品磁强计测量样品的等温剩磁(IRM)和直流退磁剩磁(DCD)曲线,经过对测量数据的处理和计算获得ΔM曲线的方法和步骤,讨论了影响ΔM测量的相关问题.最后应用该方法测量了两种TbFeCo薄膜样品的ΔM曲线,定性比较分析了薄膜晶粒间磁相互作用的大小和类型.     

基于粒子群算法和卡尔曼滤波器的PID控制

针对PID控制系统中存在参数的整定和控制干扰信号和测量噪声信号问题,提出基于粒子群算法和卡尔曼滤波算法的PID控制方法。利用粒子算法优化PID参数,通过卡尔曼滤波器抑制控制干扰信号和测量噪声信号。仿真结果表明具有响应速度快、抗干扰能力强等特点,且达到了全局最优PID参数整定,有效地剔除系统的控制干扰和测量噪声信号,具有比传统PID控制方法更好的动态和静态控制性能,控制品质有较大的改善和提高。为PID控制系统的研究提供了一种新方法。     

基于IMU的机械臂末端执行器姿态优化

为了补偿机器人关节扭转不足和末端执行器连接等造成的末端执行器姿态误差，提出一种基于惯性测量单元在线获取末端姿态的方法。首先将整个机械臂系统的运动过程分为静态和动态过程。静态时，由于外部加速度噪声较小，提出使用加速度计根据当地重力估计末端执行器姿态角的方法。动态时，针对系统外部加速度噪声和陀螺仪零漂、比例因子误差等影响测量精度的问题，提出一种基于噪声统计方法的自适应扩展卡尔曼滤波算法。根据加速度计的测量值，更新观测噪声方差阵的权重，从而调节卡尔曼增益，降低加速度噪声对测量精度的影响。实验结果表明：静态时，通过静态算法估算的姿态角误差平均值为0.07°、0.05°、0.2°;动态时，本文算法可以很好补偿外部加速度的对姿态的影响，能有效提高姿态测量精度，相比于EKF算法，姿态角平均误差分别降低了2.69°、1.01°、0.5°。     

磁性薄膜噪声测量系统研制

利用惠斯通电桥和两极放大电路在磁屏蔽腔中设计开发了磁性薄膜低频噪声测量系统。通过内推法和外比法测试证明该系统测量精度高,稳定性好,能够完成加磁场环境下的低频噪声测量。利用此系统发现各向异性磁电阻元件在退火后1/f噪声明显降低。该装置对于磁性薄膜提供了一种非破坏的有效检测手段,同时也提供了检测磁性转变内在机制的一种有效途径。     

磁记录介质晶粒磁相互作用参数△M及其测量方法

对于磁记录介质,记录噪声与晶粒间磁相互作用相关。△M是表征磁记录介质晶粒间磁相互作用的重要参数。首先介绍了它的理论依据和意义,接着阐述了通过振动样品磁强计测量样品的等温剩磁（IRM）和直流退磁剩磁（DCD）曲线,经过对测量数据的处理和计算获得△M曲线的方法和步骤,讨论了影响△M测量的相关问题。最后应用该方法测量了两种TbFeCo薄膜样品的△M曲线,定性比较分析了薄膜晶粒间磁相互作用的大小和类型。     

PIN光电管在激光外差玻璃测厚系统中的应用

为了检测激光外差玻璃厚度测量系统中的弱光信号,介绍了激光外差玻璃测厚系统原理,并用MATLAB对其进行了仿真,分析了PIN管光电检测电路噪声产生因素,提出了减小噪声、提高信噪比的方法,采用PIN管设计的光电检测电路,为激光外差玻璃测厚系统提供了一种单元模块电路.     

静态负荷模型参数分散性研究

大量现场实测负荷数据和动模数据的辨识结果表明,同一负荷成分不同扰动情况下的负荷特性数据辨识结果不稳定,有时甚至相差十几倍到百倍,即模型参数存在较大分散性.该文深入研究了负荷模型结构和负荷噪声对静态负荷模型参数分散性的影响.通过大量仿真建模实例说明了影响静态负荷模型参数分散性的原因,结果表明负荷模型结构不正确、不真实以及负荷噪声是导致静态负荷模型参数分散性的根源.     

均匀磁场强化磁性液体导热系数实验研究

将封有聚α-烯烃合成油基磁性液体的两玻璃管放置于磁场中,为消除磁场力、重力所引起的磁性液体自然对流的影响,消除端部效应,研制了磁性液体在均匀磁场中瞬态双热线导热系数的实验测量系统.实验测量了均匀磁场对不同体积浓度的磁性液体导热系数的影响.结果显示,均匀磁场显著强化磁性液体的导热系数,其导热系数随磁场强度的增加而近似线性...     

基于VC++的介质复介电常数变温测量系统软件设计

本文针对介质电参数测量自动化与精确化的需要,综述了高Q谐振腔法测量介质复介电常数的基本方法,设计了一套基于VC 的、可兼容多种矢量网络分析仪与多种形式谐振腔的介质复介电常数变温测量软件系统,并论述了具体的开发设计过程.利用不同的方法测量多组介质片对软件进行测试,测量结果表明,该方法可以提高测量效率和精度,为介质复介电常数测量提供了一种有效的手段.     

玻璃基片和石英试杆对磁光薄膜居里温度测量的影响及其消除方法

在磁光薄膜居里温度的测量中,当薄膜的磁化强度信号与石英试杆和玻璃基片的磁化强度信号具有同一有时,石英试杆和玻璃基片,对薄膜居里温度的确定引入很大的误差,提出了消除石英试杆和玻璃基片影响三种方法,实验结果表明,由三种方法消除石英试和玻璃基片影响后所确定得到的磁光薄膜居里温度相对偏差小于5％,因此,三种消除石英试杆和玻璃基片影响的方法是切实可行的。     

The development of technologies and devices for protection from noise generated by power equipment

The main lines of currently conducted research and development activities on suppressing noise produced by power-generating equipment are presented. Matters related to preventing the occurrence of aeroacoustic self-excited vibrations, optimizing dissipative noise silencers, using structural methods for damping acoustic vibrations, suppressing low-frequency noise, and analyzing the effectiveness of soundproof coatings are considered. The process diagrams and parameters of devices for suppressing noise generated during discharge into the atmosphere of high-pressure gaseous media are discussed.     

低压配电网载波通信噪声特性研究

低压电力线载波通信作为一种通信新手段,正在引起世界上电力界的广泛关注。但是,无处不在的噪音,负荷和人为的干扰以及一些不可预知的情况却严重地影响了信号的传输质量。通过使用格纳－威利分布（ＷＶＤ）时频分析法、Ｒｅｎｙｉ元素分析法,根据在不同地点,不同噪声环境取得的现场采样数据,对利用噪声来传递信号的可行性进行了初步的研究,并通过１个具体复杂噪声环境中的实例进行信号分析。最后,对高频信号在电力线中的传播     

Moldless micropatterning of BaTiO<Subscript>3</Subscript> nanoparticles via electrophoretic deposition: A simple and feasible method

In this work, a simple, reproducible, and inexpensive fabrication route for moldless micropatterning of a colloidal assembly on a conducting substrate surface is actualized by means of electrophoretic deposition (EPD) technique. A synergetic combination of photolithography and EPD is employed for fabricating micropatterns of barium titanate (BaTiO₃) nanoparticles on an indium-tin-oxide (ITO) coated glass slide or a Pt/ITO substrate. At first, high quality resist molds with various micropatterns are fabricated on ITO glass slide by photolithography technique, which is used for providing a controlled local electric field during the EPD process. Then, BaTiO₃ nanoparticles suspension is prepared in KCl aqueous solution and is demonstrated the BaTiO₃ nanoparticles are negative charged in the suspension. At last, EPD of various BaTiO₃ micropatterns is accomplished successfully on the anodic ITO glass slide or Pt/ITO substrate using the micropatterned ITO glass slide as the cathode, indicating that it is a simple and potential route for micropatterning of colloidal assembly on a non-modified conducting substrate by virtue of EPD process.     

混合信号集成电路衬底噪声的一种连续时间直接测试方法

建立了混合信号集成电路中衬底噪声对模拟电路影响的一种通用模型，在此基础上，提出了衬底噪声测试的一种新的连续时间直接测试方法。该方法采用差分放大器作为衬底噪声探测器，能测试频率高达1GHz的衬底噪声。     

On-site fabrication of ceramics films from solution precursors by ink-jet and spray assisted processes

Solution processing based on Ink-jet and spray technologies is one of low cost on-site ceramic patterns/films fabrication methods at moderate temperatures from precursor solutions. In the present study, we have used ink-jet and spray technologies to fabricate ceramic films of titania directly on glass substrates at 300–400^∘C. The precursor solution was prepared by dissolving Titanium tetraisopropoxide in appropriate solvents (water/ethanol and acetylacetone). A cleaned glass substrate was kept on a hot plate and heated it up to a predetermined temperature. Droplets of the precursor solution produced through a spray gun were traveled towards heated substrate with a atmospheric pressure. When the droplets hit on the heated substrate, precursor started to decompose, nucleate and grow into the TiO₂ film. The anatase pattern was directly obtained by ink-jet method at moderate temperatures.     

Floquet theory and non‐linear perturbation analysis for oscillators with differential‐algebraic equations

Oscillators are key components of electronic systems. In RF communication systems, they are used for frequency translation of information signals and for channel selection, and in digital electronic systems, they are used as a time reference, i.e. a clock signal, in order to synchronize operations. Undesired perturbations in practical electronic systems adversely affect the spectral and timing properties of oscillators, which is a key performance limiting factor, being a major contributor to bit‐error‐rate (BER) of RF communication systems, and creating synchronization problems in clocked and sampled‐data systems. Characterizing how perturbations affect oscillators is therefore crucial for practical applications. The traditional approach to analysing perturbed nonlinear systems (i.e. linearization) is not valid for oscillators. In this paper, we present a theory and efficient numerical methods, for non‐linear perturbation and noise analysis of oscillators described by a system of differential‐algebraic equations (DAEs). Our techniques can be used in characterizing phase noise and timing jitter due to intrinsic noise in IC devices, and evaluating the effect of substrate and supply noise on the timing properties of practical oscillators. In this paper, we also establish novel results for periodically time‐varying systems of linear DAEs, which we rely on in developing the above theory and the numerical methods. Copyright © 2000 John Wiley & Sons, Ltd.     

Structural and optical properties of CdS thin films on organic substrates for flexible solar cell applications

Cadmium sulphide (CdS) films were chemically deposited on glass, polycarbonate (PC), and polyethylene terephthalate (PET). Effects of substrate types on the structural and optical properties of the films were investigated. There is a preferential orientation of the crystallites in the film grown on the glass along the c-axis (perpendicular to the plane of the substrate) producing a strong hexagonal (0 0 2) or cubic (1 1 1) peak, regardless of the presence of ITO coating. However, such preferential orientation decrease or disappear when the deposition was made onto PC or PET substrates. PC and PET substrates exhibited the larger roughness than that for the glass because of large particles adsorbed on the PC and PET substrate. The average transmittance of the films on PC and PET is about 50%, 55%, respectively, and increases up to 70% for glass substrate. The improvement of the transmittance was obtained from ITO-coated substrates.     

Recent Japanese developments in printed wiring boards for SMT

Recent developments in printed wiring boards (PWBs) for use in surface mounting technology (SMT) in Japan are reviewed. Particular emphasis is placed on the high-density multilayer PWBs, which are important for SMT. Requirement for PWBs with respect to wiring density and housing capability, electrical properties, characteristics required at time of mounting, and reliability are discussed. Design, structure, and substrate materials are examined. The manufacture process is described. Quality assurance is addressed. Future prospects for PWBs are considered     

嵌入式高可靠性通信管理机的设计

描述一种基于嵌入式技术、无风扇、无硬盘、高可靠性通信管理机的硬件系统和软件设计。使用高性能、低功耗的硬件平台,操作系统选择裁减的Linux,通过合理的分层分布软件设计达到长期稳定运行的要求。国内正在对IEC61850体系进行研究和应用,该系统也提供对它的支持。