模拟积分器式磁通计的研究与设计

讨论了模拟积分式磁通计的原理及其在设计上的难点和关键技术，介绍了一款高精度、低零漂、高线性、多功能磁通计的设计思路和设计方法。该仪器经过检定，目前正试用于实际工作中。     

电力参数间谐波测量算法的研究

DFT的泄漏和栅栏效应不能测量电力系统的间谐波和分析电力系统谐波误差。一般通过加窗插值DFT能测量间谐波,然而需要构造窗函数使得分析及实际运行变得复杂。本文通过简单的频域变换结合多谱线插值并且给出了一种相应的算法,仿真结果表明该方法运行简单便于分析,精度高,因此为电力系统谐波分析提供了一种满意的工具。     

一种高精度低漂移电子积分器的设计

讨论了由运算放大器构成的理想电子积分器的工作原理,分析了积分漂移、积分时间常数等主要因素对积分输出误差的影响及改善措施。设计了一种测量灵敏度高达10-9 C新型电子积分器,并将该电子积分器应用于10-7C～10-8C电量微磁通信号测量系统,通过实际测量数据证明,该积分器可实现对瞬变小信号进行高精度的测量。测量精度达到满量程小于1.5%,分辨率为0.5%,而且该设计方案结构简单、灵敏度和精度高、经济性好,有很好的推广使用价值。     

积分器系统在软磁合金磁性测量中的应用

本文研究了应用积分器系统对软磁合金磁性测量的方法.分析了积分漂移,积分时间常数等主要因素对积分误差的影响,设计出测量精度达到10-9C电荷量的电子积分器,以达到对软磁合金磁性测量的要求.采用了0.01H的标准互感对积分系统标定的方法,并完成了软磁合金1J85材料的标准样品进行饱和磁感应强度Bs的测量比对实验,系统测量精度达到1.8%,满足测量要求.     

工作台倾斜对角度测量的影响分析及应用

工作平台的倾斜会导致自准直仪在配合转台进行角度测量时产生测角误差,研究该倾斜引起的误差规律不仅对提高测角精度具有重要意义,还对实现测角仪器的标定具有参考价值。论文首先基于三个状态参数(平面倾斜角θ_p、反射面方位角θ_x、反射面垂直度?),通过齐次坐标变换推导建立转台配合自准直测角时由平台倾斜导致的误差数学模型;接着以模型中的θ_x为自变量,在不同量级的θ_p、?的取值下仿真得到多组误差曲线,对比分析并总结该误差的分布规律;最后,基于该误差的特性提出一种自准直测角标定方法,分析表明,取反射面方位角θ_x=90°时,该方法可实现每步大小为θ_p·?的角度改变量,是标定自准直仪的一种可行途径。     

谐波对相位测量的影响

本文着重介绍谐波对以测量过零时间间隔、基波相位差、有效值功率与视在功率之比为基础的３种工作原理的相位测量仪表的影响机制和使用中应注意的问题。     

采用超低失调运放的集成积分器的设计与实现

采用特殊技术方法控制二级运放中特定MOS管尺寸,设计出一种超低失调电压的运算放大器,并将其应用到集成积分器的设计.然后基于理想积分器的工作原理,用一种新的方法,设计并实现了一种有超低失调运放的集成积分器.设计采用HHNEC0.18μm CMOS工艺,在Cadence环境下利用Hspice进行仿真,结果显示,运放失调为556nV,增益以及相位稳定裕度较大;积分器在1kHz频率工作时显示出良好的工作特性.版图设计考虑了失配与匹配的问题,并且通过了DRC和LVS规则检查.     

随机参数诱导交流积分器中的随机共振研究

研究了具有随机参数的交流积分器中的随机共振现象。基于线性系统理论,得到了系统输出信噪比的表达式。研究发现,输出信噪比是噪声强度、噪声相关率以及系统参数的非单调函数。信噪比随着激励信号频率的增大而增大,随着信号直流分量的增大而减小。     

谐波失真对振动测量值的影响

本文利用泰勒级数及一些数学推导 ,对加速度、速度、位移三种波形失真度之间的关系及其各自对测量值的影响进行了分析与估算     

Digital Integrator for Fast Accurate Measurement of Magnetic Flux by Rotating Coils

A fast digital integrator (FDI) with dynamic accuracy and a trigger frequency higher than those of a portable digital integrator (PDI), which is a state-of-the-art instrument for magnetic measurements based on rotating coils, was developed for analyzing superconducting magnets in particle accelerators. Results of static and dynamic metrological characterization show how the FDI prototype is already capable of overcoming the dynamic performance of PDI as well as covering operating regions that used to be inaccessible     

脉冲漏磁无损检测影响因素分析

脉冲漏磁无损检测系统可以用来检测带保温层管道的腐蚀缺陷,其主要参数的设计对提高系统的检测性能具有重要意义。分析了检测线圈尺寸、激励脉冲信号的频率、电压、占空比以及边缘效应等因素对检测结果的影响,给出了检测结果随这些因素的变化规律,为系统参数的优化设计提供了依据。     

Influence of Slot Defect Length on Magnetic Flux Leakage

A key issue, which influences the applications of magnetic flux leakage testing, is defect quantification. There have been many research on the relationship between width, depth and magnetic flux leakage of slot defect. However, the length factor is often ignored. The relationship between characteristics of defect leakage field and defect length was investigated. The magnetic flux leakages of a series of plate specimens with the same width, same depth and different length slot defects were tested under the same magnetizing conditions. Testing results show that defect length is an important parameter needed to consider in quantifying defects.     

Simulation and Analysis of 3-D Magnetic Flux Leakage

In this paper, we present simulation results and analysis of 3-D magnetic flux leakage (MFL) signals due to the occurrence of a surface-breaking defect in a ferromagnetic specimen. The simulations and analysis are based on a magnetic dipole-based analytical model, presented in a previous paper. We exploit the tractability of the model and its amenability to simulation to analyze properties of the model as well as of the MFL fields it predicts, such as scale-invariance, effect of lift-off and defect shape, the utility of the tangential MFL component, and the sensitivity of MFL fields to parameters. The simulations and analysis show that the tangential MFL component is indeed a potentially critical part of MFL testing. It is also shown that the MFL field of a defect varies drastically with lift-off. We also exploit the model to develop a lift-off compensation technique which enables the prediction of the size of the defect for a range of lift-off values.      

场量测量在变交漏磁检测技术中的应用

介绍了以AD637为基础建立的交变漏磁场测量调理电路,完成了基于A3515霍尔元件的漏磁场场量测量传感器的设计,阐述了交变漏磁场测量的工作原理和测试方法,通过对钢管矩形裂纹的测试结果表明,该设计实现了测试的目的,在对缺陷信号进行分析和处理的基础上,提出了基于"缺陷环"的识别方法.     

AC Magnetic Technique to Measure Specific Absorption Rate of Magnetic Nanoparticles

The electrodynamic method is applied to determine the specific absorption rate (SAR) of an assembly of superparamagnetic nanoparticles as a function of frequency and magnetic field amplitude. The home made frequency-adjustable electromagnet is used to create a nearly uniform magnetic field in a core gap of a volume 1×3×3 cm³ in the frequency range f=10–150 kHz and for magnetic field amplitudes up to H ₀=250 Oe. Two oppositely connected pick-up coils are used to record the electromotive force signal (EMF) generated by magnetic nanoparticles. By integrating the EMF signal one can determine the low-frequency hysteresis loops of the assembly and the assembly SAR. Using this method the measurement of SAR has been carried out for magnetite nanoparticles with an average diameter D=25 nm. The electrodynamic method is shown to be capable of measuring a small amount of magnetic nanoparticles, up to 5×10^?5 g, dispersed in a solid matrix. The maximal SAR ～?80 W/g has been obtained for the magnetite nanoparticle assembly investigated.     

Boxcar积分器模型参数软件在nS荧光测量中的应用

利用计算机运算速度快,描述形象的特点设计Boxcar模型参数选择软件。我们利用该软件进行了一系列实验,对被恢复波形的要求灵活地选择、计算或修正参数值,给相关工作带来了很大的方便。     

Dipole Modeling of Magnetic Flux Leakage

In this paper, we present an analytical model to represent the 3-D magnetic flux leakage (MFL) field due to the occurrence of a surface-breaking defect in a ferromagnetic specimen. This situation is frequently encountered in the nondestructive evaluation (NDE) of energy pipelines using the MFL technique. The model is derived from first principles, and utilizes the concept of dipolar magnetic charge induction to yield the 3-D MFL field in terms of surface integrals. The magnetic flux density in the specimen is assumed to be in the saturation region, and the permeability is assumed to be locally constant in the vicinity of the defect. The model uses just two geometric parameters and is capable of reproducing results that have been obtained experimentally in the literature. 3-D MFL field simulations obtained from the model facilitate a better understanding of the effect of a surface-breaking defect on the magnetic field in its vicinity. Furthermore, we simulate and analyze the 3-D MFL field in the 3-D space around the defect. This analysis yields numerous properties regarding the spatial characteristics of the three orthogonal components of the MFL field of the defect.      

磁通 e-HR 神经元模型的放电行为及同步控制

以 e-HR 神经元模型为基础,在考虑外界电磁场对神经元膜电位变化的影响下构建磁通 e-HR 神经元模型。首先,利用盛金公式来求得磁通 e-HR 神经元模型平衡点个数以及对其平衡点稳定性进行了研究,同时进一步利用分岔理论找出系统发生分岔时的条件。其次,通过改变外加刺激电流以及磁通反馈增益,发现神经元呈现出簇放电、周期放电等多种放电模式。此时平衡点的不稳定状态对应为神经元放电模式;稳定状态对应静息模式,即不放电模式。最后,基于Lyapunov稳定理论设计自适应控制器,通过理论分析和数值仿真证明了控制器的有效性与可行性。     

Performance Improvement of a DSP-Based Digital Integrator for Magnetic Measurements at CERN

An improved self-calibrating digital instrument for online flux measurements on superconducting magnets for particle accelerators prototyped at the European Organization for Nuclear Research (CERN), in cooperation with the University of Sannio, is presented. The new instrument reduces the online flux analysis time down to 4.00 $muhbox{s}$ within a resolution of 50 ns. Furthermore, the typical signal-to-noise-and-distortion ratio (SINAD) is significantly improved with respect to the previous version and to the instruments that are currently in use. Details about the design, online measurement principle, and results of the metrological characterization of the new instrument are provided.