一种基于PIC16C63的高精度智能液位传感器

介绍了一种高精度的智能液位传感器，其工作原理为：在超声探头(型号为5P14)上施加一负电压脉冲信号，探头发出脉冲超声波，当遇到不同介质界面的时候超声波被反射，回波信号被超声探头接收，转换成脉冲电压信号．利用PICl6C63单片机的捕捉功能来计算超声波回波与发射波之间的时间，进而计算出超声波在液体中传播的距离，实现对液位的精确测量。该传感器测量精度高，性能稳定可靠。     

分立型电压电流探头的原位标定

利用分立型电压、电流探头和数字示波器测量脉冲射频功率存在探头相位标定的问题,造成难以精确测量脉冲射频功率,特别是脉冲射频放电初始击穿段的功率。文中研究了影响探头相位标定的因素,获得了分立型电压、电流探头相位校正因子。经过比较,测量的脉冲射频功率与光电倍增管记录的放电辉光变化规律基本一致,证实了标定后的分立型电压、电流探头可以用于脉冲射频功率精确测量。     

基于有限元仿真的涡流探头特性研究

涡流检测在工业生产及设备运行维护等无损检测技术领域占有重要地位。文中介绍一种用于无损检测的涡流探头,探头由1个激励线圈与2个接收线圈组成。激励线圈在电压信号的激励下,在试件中产生感应涡流,试件中涡流随缺陷发生变化,接收线圈捕获到涡流产生磁场的变化,以此分辨试件表面缺陷。分别对涡流探头的激励线圈、接收线圈进行理论分析,使用有限元仿真软件Maxwell对传感器进行建模与仿真。采用数值方法分析探头在正弦波电压激励下的工作方式,铝试件与Q235试件表面涡流分布与探头输出特性。仿真分析了涡流效应对Q235材料探头输出的影响。对Q235试件中不同缺陷深度对探头输出电压大小的影响进行了分析。根据仿真结果,进行了探头实物制作,获得了探头在不同缺陷深度的输出信号,通过实验验证了探头对缺陷检测的有效性。     

射频气体放电激励电压电流及相位传感器的研制

由于分布电容的存在而造成对仪器的干扰，使得对射频放电电压电流及相位的测量，到目前为止仍然是比较困难和昂贵的；使用简单的电压电流探头而无干扰地精确地测量出电压、电流和相位角，从而计算出复合阻抗几乎是不可能的。这里介绍一种自行研制的传感器，结合网络分析理论，采用数字与计算机技术实现对射频放电电压、电流及相位角精确的测量，经实际使用精度高，抗干扰能力强，价格低廉。     

非晶态合金材料的磁通门磁强计探头

本文综述了正弦信号激励的磁通门跑道型探头输出二次谐波电压灵敏度公式。从这个讨论出发,有可能寻找新探头工作物质。本文介绍选用非晶态合金代替玻莫合金绕制成磁通门磁强计探头,并对它进行直流、交流磁性能及电压输出灵敏度的测试。最后把这种材料与通常磁通门磁强计所采用的1J86玻莫合金进行分析对比。结果表明,非晶合金作为磁通门磁强计探头材料是大有希望的,且许多性能优越于玻莫合金。     

工业电导信号测量仪的研制

提出了一种基于新的激励模式的电导信号测量仪.该装置采用双极性脉冲电压源作为激励源,与交流激励的电导测试系统相比,削弱了介质电极化现象,简化了电路设计,并提高了数据的采集速度和精度.同时还专门设计了具有防腐、避免电化学反应及带有温度补偿的专用电导测量探头.经测试,该系统测量准确、抗干扰能力强,满足了工业流程中溶液电导特性的实时测量要求.     

异步电机模型Matlab仿真

用Matlab／Simulink搭建异步电机模型，将SPWM波代替正弦电压源并且构建SPWM仿真模型，仿真结果表明，三角波频率越高，电流波越圆滑，越接近正弦波，验证了正弦电压源下模型的正确性。     

一种提高FLUKE5500电压负载能力的方案

本文介绍一种用于提高FLUKE550电压负载能力对电压的电流扩展电路设计，解决了一般电压源负载能力不足的问题。     

巧用假轴调整M3387A压缩机振动探头间隙

我厂烷基化装置的M３３８７A型制冷压缩机为四级离心式压缩机，结构非常紧凑，前部结构如图１所示。水平中分式壳体，整圆锥形的前端盖；前轴承、机械密封等都安装在固定于前端盖中心的小锥体内；前端有一段靠螺纹与主轴联接的短轴，用来传递扭矩。该机２００１年因机体吸入酸（催化剂）后进行了大修，检修至最后阶段，安装前轴承部位的轴振动探头却成了难题。因为安装这种本特利电涡流型探头要求转子及轴承部分均已固定且处于正常工作位置，然后靠探头上的螺纹将探头端部与轴颈之间的间隙调至０．８～１mm（以间隙电压为准）。然而因轴承…     

为万用表增加交流低电压测量档位

利用二极管峰值检波电路与电阻分压器组成的探头,将输入的交流电压U转换成大小等于输入信号电压有效值U的直流电压,以此增加万用表交流低电压的测量档位.     

收尘用高压电源的比较分析和优化设计

为使电场强度满足工况要求,粉尘荷电效果理想,特分析了不同高压电源的技术特性,在此基础上设计了由4个电场组成的静电收尘设备并加以优化,其第一个电场由高频高压脉冲电源供电,其余电场由适合高比电阻的恒流源供电.经投入运行证明相关分析符合实际情况,该项设计满足使用要求.     

Acoustic velocity measurements in resonators of thermoacoustic systems using hot-wire anemometry

Acoustic velocity measurements in resonators of thermoacoustic systems using hot-wire anemometry technique flow are presented. The hot-wire calibration is based on the determination of the acoustic velocity reference value through an acoustic pressure measurement and their relationship using a linear acoustic model. In this model, an analytical approach involving the coupling between the sound source and the resonant cavity effects and the viscous and the thermal effects in the boundary layers is used. The amplitude and phase calibrations are reported for the first time, simultaneously, either by varying the sound source input voltage for a fixed frequency, or by varying the frequency for a given source input voltage. The amplitude calibration is detailed by using a filtering technique to eliminate either the acoustic streaming effects or the anemometer basic electric voltage variations effects. This provides a simple way to an amplitude calibration with good accuracy when measuring an average of a stationary oscillating velocity. The phase calibration is proposed here by considering the phase difference between the microphone and the hot-wire anemometer output signals. The results obtained by using a simple fluid-filled resonant cavity are encouraging on the feasibility of this method to carry out a first-order acoustic velocity measurement. However, the complexity of the dynamic calibration due to that of the heat transfer mechanism around the hot-wire probe in various frequency ranges clearly merits more investigation.     

一种基于电场测量的无损检测方法

提出一种基于电场测量的无损检测方法,该方法通过检测通电试件外电场的变化来实现内外缺陷的非接触检测。对通电试件的电场进行仿真计算,模拟出电场的分布并分析了缺陷电场的信号特征。以半导体材料为被测试件,在高电压激励下采用被动式的共面电容探头探测到了内外缺陷的电场信号。实验与仿真结果的一致性表明,采用该方法对金属和非金属材料进行内外伤的检测具有一定的可行性。     

Electron density measurement of cesium seeded negative ion source by surface wave probe

Electron density measurements of a large-scaled negative ion source were carried out with a surface wave probe. By comparison of the electron densities determined with the surface wave probe and a Langmuir probe, it was confirmed that the surface wave probe is highly available for diagnostic of the electron density in H(-) ion sources. In addition, it was found that the ratio of the electron density to the H(-) ion density dramatically decreases with increase of a bias voltage and the H(-) ions become dominant negative particles at the bias voltage of more than 6 V.     

基于阻抗变换的非接触电压测量自校准方法

电容耦合式非接触电压测量在实际测量中,探头-导线之间的耦合电容受导线线径、绝缘材质、相对位置偏差的影响,造成分压关系难以确定从而无法准确重构电压。本文提出一种基于阻抗变换的非接触电压测量自校准方法,以实现在实际测量中传感器增益的自标定。首先介绍电容耦合电压测量的基本原理,从中凝练存在的问题并提出基于阻抗变换的自校准方法,随后通过仿真对系统参数进行校准精度影响分析并给出参数选取原则。在此基础上,开发传感器探头及电路拓扑。最后进行传感器样机精度测试、抗干扰能力测试、场景适应性测试,精度测试显示电压幅值最大相对误差为0.59%,相位相对误差为0.76%,抗干扰能力测试表明同轴探头对周围耦合电场具有良好的屏蔽作用。场景适应性测试显示在进行不同类型线路的测试中,最大相对误差为1.24%。     

Design and operating characteristics of new type cold cathode ion source

In this work, the design and performance of new type ion source are described. The discharge mechanism of the source is based on creating an arc discharge through a saddle electric field inside the discharge tube. The saddle electric field is created by immersing an annular anode inside the discharge tube covered from the upper and lower ends with two flanges. These two flanges act as cathodes. The discharge tube is surrounded by a solenoid coil which produces an axial magnetic field (up to 400 G) measured at the center of the source. Measurements have been performed to find out the influence of arc power, pressure, discharge voltage, magnetic field, and extracting voltage on the ion source properties. The source yields an argon ion current of approximately 0.6 mA and electron current of approximately 4 mA at normal operating conditions (extraction voltage V(ex)=7 kV, pressure of 5.5x10(-4) Torr, V(arc)=400 V, I(arc)=1 A, B=200 G). It showed an energy spread of 20 eV at a discharge voltage of 400 V and an extraction voltage of 3 kV.     

Dynamical changes of ion current distribution for a Penning discharge source using a Langmuir probe array

A paralleled plate electrode and a 9-tip Langmuir probe array located 1 mm behind the extraction exit of a cold cathode Penning ion source are employed to measure the total current and the dynamical changes of the ion current in the 2D profile, respectively. Operation of the ion source by 500 V DC power supply, the paralleled plate electrode and the Langmuir probe array are driven by a bias voltage ranging from -200 V to 200 V. The dependence of the total current and the dynamical changes of the ion current in the 2D profile are presented at the different bias voltage. The experimental results show that the distribution of ion current is axial symmetry and approximate a unimodal distribution.     

In situ metal tip sharpening of scanning probe microscopes

This article demonstrated a new approach for fabrication and sharpening of metal tips of scanning probe microscopes. Experimentally, a metal tip was heated and melted by a focused laser light. The tip was then sharpened by a strong electric field and consolidated as the laser was turned off. With a low‐vacuum and a high‐voltage source, a 25‐µm indium‐coated platinum wire was sharpened to a tip with diameters below 50 nm. The minimal tip radius by this method is estimated to be below 1 nm. With this technique, in situ tip sharpening for SPM would be possible. SCANNING 34: 76–79, 2012. © 2011 Wiley Periodicals, Inc.     

A high-voltage system of a differential spectrometer for measuring the neutron electric dipole moment

A system of hardware and software for supplying a bipolar high voltage of up to 200 kV to a differential spectrometer that measures the neutron electric dipole moment is described. The high-voltage source is based on two 10-cascade voltage multipliers using quasi-resonant technology. The hardware and application software allow operation of the system in the manual, semi-automatic, and automatic modes.     

Probe Diagnostics of a Rotating Plasma

A technique for making probe measurements of the parameters of a plasma rotating in crossed radial electric and axial magnetic fields is described. Unlike the commonly used method, the processing of readings of the Langmuir triple probe was carried out using the results of measurements based on a Mach plasma probe. When using a magnetic field produced in a solenoid without end-to-end magnetic plugs, a positive potential with respect to the grounded anode and outer metal tube is observed in the plasma that arrives from the electric discharge source with the thermoemission cathode and the annular anode. It is shown that the speed of azimuthal electron drift in the crossed-fields system under investigation is much higher than the ion rotation speed.