Void Fraction Measurement in Oil-Gas Transportation Pipeline Using an Improved Electrical Capacitance Tomography System

To measure the void fraction online in oil-gas pipeline, an improved electrical capacitance tomography (ECT) system has been designed. The capacitance sensor with new structure has twelve internal electrodes and overcomes the influence of the pipe wall. The data collection system is improved by using high performance IC (integrated circuit). Static tests of bubble flow, stratified flow and annular flow regime are carried out. Measurements are taken on bubble flow, stratified flow and slug flow. Results show that the new ECT system performs well on void fraction measurement of bubble flow and stratified flow, but the error of measurement for slug flow is more than 10%.

Application of Electrical Capacitance Tomography to the Concentration Measurement in a Cyclone Dipleg

Accurate solid concentration measurement plays a key role in the process industry. Measurements analyzed offline can be used to estimate process efficiencies, to identify problems in a flow, and to validate computational models. Online measurements can be used for active control. Electrical capacitance tomography （ECT） is a unique measuring technique with great potential in multiphase flow measurement. Experimental studies are carried out on a solid concentration measurement in a cyclone separator dipleg, using ECT. In this experiment eight electrodes are selected for the ECT sensor that is placed on the straight tube of the dipleg. The fluctuating characteristics according to the screw feeder and the effect of the airflow rate from the top of the cyclone are analyzed. The feasibility andreliability of the method are verified by the experimental results.

Liquid holdup measurement with double helix capacitance sensor in horizontal oil-water two-phase flow pipes

This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.

Characterization of Interface State Density of Ni/p-GaN Structures by Capacitance/Conductance-Voltage-Frequency Measurements

For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.

Illumination and Voltage Dependence of Electrical Characteristics of Au/0.03 Graphene-Doped PVA/n-Si Structures via Capacitance/Conductance-Voltage Measurements

Au/n-Si （MS） structures with a high dielectric interlayer （0.03 graphene-doped PVA） are fabricated to investigate the illumination and voltage effects on electrical and dielectric properties by using capacitance-voltage （C-V） and conductance-voltage （G/w-V） measurements at room temperature and at 1 MHz. Some of the main electrical parameters such as concentration of doping atoms （ND）, barrier height （ ФB（ C - V） ）, depletion layer width （WD） and series resistance （Rs） show fairly large illumination dispersion. The voltage-dependent profile of surface states （Nss） and resistance of the structure （Ri ） are also obtained by using the dark-illumination capacitance （Cdark- Cm） and Nicollian-Brews methods, respectively, For a clear observation of changes in electrical parameters with illumination, the values of ND, WD, ФB（O- V） and Rs are drawn as a function of illumination intensity. The values of ND and WD change almost linearly with illumination intensity. On the other hand, Rs decreases almost exponentially with increasing illumination intensity whereas ФB（C - V） increases. The experimental results suggest that the use of a high dielectric interlayer （0.03 graphene-doped PVA） considerably passivates or reduces the magnitude of the surface states. The large change or dispersion in main electrical parameters can be attributed to generation of electron-hole pairs in the junction under illumination and to a good light absorption. All of these experimental results confirm that the fabricated Au/0.03 graphene-doped PVA/n-Si structure can be used as a photodiode or a capacitor in optoelectronic applications.

New Method of Measuring the Positive-sequence Capacitance of T-connection Transmission Lines

A novel method of measuring the positive-sequence capacitance of T-connection transmission lines is proposed. The mathematical model of the new method is explained in detail. In order to obtain enough independent equations, three independent operation modes of T-connection transmission lines during the line measurement are introduced. The digital simulation results and field measurement results are shown. The simulation and measurement results have validated that the new method can meet the needs of measuring the positive-sequence capacitance of T-connection transmission lines. This method has been implemented in the newly developed measurement instrument.

The Evaluation of Measurement Uncertainty and Its Application in the Vacuum Pressure Measurement

In order to accurately measure the pressure and the pressure difference between two points in the vacuum chamber, a large number of experimental data were used to research the performance of the three capacitance diaphragm gauge and analysis the main influences of the uncertainly degree of pressure in the process. In this paper, three kind of uncertainty, such as the single uncertainty, the synthesis uncertainty and the expanded uncertainty of the three capacitance diaphragm gauges are introduced in detail in pressure measurement. The results show that the performance difference of capacitance diaphragm gauge can be very influential to the accuracy of the pressure difference measurement and the uncertainty of different pressure can be very influential to pressure measurement. That for accurately measuring pressure and pressure difference has certain reference significance.

A dC/dV Measurement for Quantum-Dot Light-Emitting Diodes

We present dC/dV analysis based on the capacitance-voltage(C–V)measurement of quantum-dot lightemitting diodes(QLEDs),and find that some key device operating parameters(electrical and optical turn-on voltage,peak capacitance,maximum efficiency)can be directly related to the turning points and maximum/minimum of the dC/dV(versus voltage)curve.By the dC/dV study,the behaviors such as low turn-on voltage,simultaneous electrical and optical turn-on process,and carrier accumulation during the device aging can be well explained.Moreover,we perform the C–V and dC/dV measurement of aged devices,and confirm that our dC/dV analysis is correct for them.Thus,our dC/dV analysis method can be applied universally for QLED devices.It provides an in-depth understanding of carrier dynamics in QLEDs through simple C–V measurement.

Development of timer based on liquid level measurement system

This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i. e. the ON time pulse width of the timer output waveform which is measured using a digital storage oscillator （DSO）,is linearly proportional to the capacitance of a co-axial cylindrical capacitive transducer, and this capacitance once again linearly varies with the change in liquid level. Hence, we obtain a linear relationship between the liquid level and the capacitor charging time. The main advantages of this developed system are linear input-output relationship, small in size, easily portable, cost effective, and independent on the ambient temperature effect. The system can also be exploited to measure dielectric constant of liquid or solid in various process industries.

Automated Calibration of RF On-Wafer Probing and Evaluation of Probe Misalignment Effects Using a Desktop Micro-Factory

A fully automatic setup for on-wafer contact probing will be presented. This setup consists of six automatable nano positioning axes used as tool holder and a sample holder. With this setup a fully automatic one-port SOL calibration for a Vector Network Analyzer is done. Furthermore a fully automated on-wafer contact probing is performed. Afterwards, the effects of a misalignment of the three tips of a GSG-probe are examined. Additionally the error on the calibration is calculated to determine its effect on the measurement. The results show, that a misalignment of the probe has a high impact on the measurement of the VNA. Hence a fully automated on-wafer probing presented in this paper is a good way to detect these misalignments and correct them if necessary.

Analysis and Application of the Synthetic Relative Measuring Method in On-Line Monitoring for Capacitive Equipment in Power Systems

On-line measurement for dielectric loss angle can effectively monitor the insulation condition of capacitive equipment in power systems. Synthetic relative measuring methods not only markedly overcome the shortcomings of traditional absolute measuring methods but also greatly improve the accuracy of dielectric loss angle measurement. However, synthetic relative measuring methods based on two or three pieces of capacitive equipment do not have the characteristic of generality. In this paper, a principle of synthetic relative measuring method is presented. The example of application for synthetic relative methods based on three and four pieces of capacitive equipment running in the same phase is taken to present the failure judgment matrices for N pieces of equipment. According to these matrices, the fault condition of N pieces of capacitive equipment can be watched, which is more general. Then some problems needing to be concerned along with two diagnostic methods used in diagnostic system are introduced. Finally, two programmable flow charts for the two methods are given and corresponding examples demonstrate their feasibility in practice.

Glass Thickness Measurement Instrument and Optical Fiber Transmission

A system for glass thickness measurement is introduced.The signal acquisition part of the system adopts parallel plate capacitor,and measured signals are transformed into pulse frequency by capacitance-frequency transformation circuit,then transmitted it in optical fibers.So this system has high speed,high precision and high resistance to interference.

电气设备剩余电压测试仪校准方法

分析了电气设备剩余电压测试仪基本原理,提出一种基于标准阻容网络法对剩余电压测试仪剩余电压幅值和延迟时间参数进行校准的方法。结合交流标准电阻器和电容器等效模型,分析了标准电阻时间常数和标准电容损耗因数对校准结果的影响,推导了校准时剩余电压和延迟时间标准值的计算方法。采用1 MΩ交流标准电阻和1μF标准电容器组成的电路网络对剩余电压测试仪进行了校准,结果表明标准阻容网络法可满足该仪器的校准。对测量结果进行了不确定度分析,剩余电压幅值测量不确定度为1.1%,延迟时间测量不确定度为1.2%,主要不确定度分量为标准电容器损耗因数的影响。

基于深层小波网络的电容层析成像图像重建

提出了一种基于深层小波网络的电容层析成像(ECT)图像重建算法,采用Landweber算法生成初始重建图像作为网络输入;以U-Net深度卷积神经网络模型为骨干模型,通过在上、下采样层引入小波变换提取不同层次的特征,以及采用跳跃连接方式搭建高频特征传递通道,保留更多的细节信息,充分利用特征图中的全局和局部信息特征。仿真及静态实验结果均表明,基于该算法的图像重建精度更高,仿真及静态实验重建图像的平均相对图像误差分别为0.1918及0.6570,平均相关系数分别为0.9685及0.8169。

基于多尺度密集连接网络的电容层析成像图像重建

为求解电容层析成像中的非线性病态反问题,提出了一种多尺度密集连接网络(MD-Net)模型。该模型由多尺度特征融合模块和密集连接块组成,以通过融合多尺度特征进一步提高图像的重建精度。通过MATLAB仿真实验平台构建了流型数据集,利用密集连接网络的非线性映射能力,完成训练集的学习与训练,并利用测试集进行训练效果评价。在此基础上进行了静态实验。仿真与静态实验结果均表明:与LBP、Landweber迭代算法和其他深度学习方法相比,该方法的重建精度最高、抗噪能力强,并具有良好的泛化能力。

基于多尺度自适应网络的ECT图像重建

为求解电容层析成像(ECT)中的非线性病态反问题,提出了一种多尺度自适应网络(MSANet)模型,该模型实现了更精细维度上多尺度特征的融合,且模型参数量相对较小。通过在单个残差块内构建树状结构组成多尺度特征融合模块,MSANet实现了更好的鲁棒性和更低的计算参数量;采用加入自适应空间阈值模块方式,进一步提高了图像的重建精度。实验结果表明:与线性反投影(LBP)算法、Landweber迭代算法及常用深度学习方法相比,该方法平均相对误差最小且平均相关系数最大,分别为0.181及0.967。

基于两步正则化Gauss-Newton迭代算法的ECT图像重建

电容层析成像(ECT)技术求解图像重建问题属于非线性问题,并且存在严重的不适定性。为提高图像重建精度,提出了一种基于两步正则化Gauss-Newton迭代算法的ECT图像重建方法。针对标准正则化Gauss-Newton迭代算法在图像重建中存在的不收敛问题,引入了两步迭代方法;改进了正则化矩阵,提高了解估计的精确度;考虑到Gauss-Newton算法对迭代初值的依赖性,加入了同伦算法。最后,进行仿真和静态实验,并与线性反投影(LBP)算法、Landweber算法、Tikhonov正则化算法进行对比。结果表明,该方法可有效提高图像重建精度。

麻家边水库库容测量与变化分析

以麻家边水库为例,根据中小型水库库容测量的工作内容,探讨无人机载激光雷达测量、无人船自动测量、等高线法和不规则三角网法等先进方法在水库库容测量中的应用,并通过实地调查和对比不同时间的卫星影像资料合理解释水库库容变化,可为类似项目提供有益参考。

基于离散马尔可夫模型的液位感测系统分析

阐述一种新的测量原理及测量电容结构,其利用模型计算传统式电容液位测量方法中测量介质介电常数数据,分析定期标定的原因。新系统根据液位变化、介电常数、电容量关系,实现高精度测量。

电容层析成像测量甲醇制烯烃催化剂床层温度

甲醇制烯烃作为煤制烯烃的关键一环,对实现煤炭的综合利用有重要意义。这一过程是典型的放热反应,为提高甲醇转化率与产物选择性,需对床层温度进行在线监测。基于高温电容层析成像,提出一种在线测量催化剂床层温度(DMTO工业催化剂,ZSM-5分子筛)的方法。通过与介电常数变化极小的石英砂、氧化铝等床层材料的测量结果对比,发现不同催化剂的介电常数随温度变化规律不同,催化剂床层的测量电容值随温度变化敏感且重复性较好。因此可通过高温电容层析成像装置测量温度分布均匀的床层归一化电容平均值实现对床层温度的测量。通过采用薄壁石英管的固定反应器,对甲醇制烯烃催化剂、ZSM-5分子床层进行在线测温验证了该方法的有效性,发现通过线性反投影算法重构的ECTt图像,可获得床层温度分布。由此,可以通过高温电容层析成像装置实现对固定床床层床层测温。