微机控制工频方波交(直)流电源的研究

本文就工频方波交(直)流电源用微机控制进行了试验,筒述了应用计算机控制方波电源主回路电流输出以及焊接时序的方法,并就输出电流的静态精度要求,对可控硅控制角的量化问题进行了分析,给出了相应的控制算法及程序设计的原则与流程图。实验结果表明,利用微机控制该种电源的外特性、脉冲电流,交流正负半波电流比的调节及焊接程序是完全可以实现的,且其静态控制精度及参数调节灵活性均优于普通电子电路控制。     

直流标准功率源校准方法的研究

本文介绍了直流标准功率源的组成,讨论了直流标准功率源的校准方法并给出了不确定度的评定.     

大气压交流气液两相滑动弧放电特性

滑动弧放电可以在大气压下产生低温等离子体,在能源、环境及医学等领域具有广阔的应用前景。本工作对大气压交流气液两相滑动弧放电图像和多因素影响放电特性的规律进行了实验研究,通过对电信号进行快速傅里叶变换(FFT),分析放电过程中能量注入特点。研究结果表明:气液两相滑动弧放电稳定,与气相滑动弧相比放电强度减弱,但是等离子体分布均匀,出现明亮斑点;放电电流信号特征发现,滑动弧放电过程包括击穿伴随滑动模式和稳定滑动模式,与气相滑动弧放电相比,气液两相滑动弧的滑动周期变长;放电电压和电流信号的频谱分析发现,气液两相滑动弧放电电压和放电电流谐波的含量相比气相滑动弧放电明显减少,放电稳定性提高;气体流量和峰值电压对平均放电功率的影响规律与相同条件下气相滑动弧放电基本一致,增加液体流量和水溶液电导率,雾化液滴在放电过程中对高能电子的吸附作用增强,使得平均放电功率下降。     

弧焊电源变压器绕组温升快速测量的新方法

针对弧焊电源主器绕组温升检测需要进行绕组电阻值精确测量的问题，本文在恒温源法和双臂电地的基础上，利用计算机速测试物特性，提出了比较法的测量方案，由于孤焊电源器绕组可等效为电感Ｌ与电阻Ｒ的率联电路，当一恒流流过时，电流达到稳定的时间较长，根据阻尼振荡的大批量，Ｒ－Ｌ与一电容Ｃ构成欠阻尼的二阶系统，可使由电感引起的过渡过程的稳定时间缩短在一秒钟以内，从而实现了对绕组温升的快速，准确测量。     

A Precision Stabilized Sine-Wave Source for AC Power Measurements

The design of a stable sine-wave source for error determination of ac-measuring instruments is discussed. The electronic amplitude control circuit has been constructed using standard integrated circuits. The fluctuations of its rms output voltage, observed over the period of 1 h, are 1 · 10-6 peak-to-peak. Since the total harmonic distortion is less than 1 · 10-3, its contribution to the error of the rms value may be neglected.     

A New Method for Measuring the Level Dependence of AC Shunts

We report on a new method for the measurement of the level dependence of the ac–dc difference of current shunts. The method is based on the use of a binary inductive current divider. A method to compare two ac shunts at common ground is described. Measurement results on two 1-A ac shunts, which consist of different numbers of resistors, indicate that the level dependence between 0.5 and 1 A is less than 2 $muhbox{A/A}$ with an uncertainty of less than 7 $mu hbox{A/A}$ from 1 to 100 kHz.      

Method of Measuring the Mass Discharge and Consistency of a Flow Carrying A Suspension

A method is developed for determining the mass discharge and consistency of a pipe flow carrying a suspension under pressure. Mass discharge and consistency are determined by using readings of the power used by the hydraulic dredger which moves the flow.     

智能仪器测量信号功率的不确定度评定模型

针对基于交流采样原理的智能仪器,提出一种新的测量不确定度评定模型。以信号功率测量为例,受硬件条件以及信号频率波动的影响,无法确保同步采样,利用已有测量算法将使测量结果出现误差。将该误差视为系统效应,通过近似处理,提出简单且实用的修正算法。将测量过程中的量化噪声、信号传输中的干扰当作具有已知分布特征的随机变量,利用统计方法,并依据测量不确定度传播定律,评定了经修正算法修正后的测量结果的不确定度。这种先修正系统效应、再评定随机因素造成不确定度的模型,更符合测量过程的实际情况。物理实验和仿真计算均验证了所得结论的有效性。     

Study the Performance of the AC/DC Resistors During Their DC and AC Measurements

Some of traceability chains for the AC resistance measurements are based on AC/DC resistors. In this paper, performance of two types of them with different values has been investigated for their optimum utilization. Tinsley and Cambridge AC/DC resistors have been measured as DC resistors using different measurement methods and as AC resistors at various frequencies. DC direct method using digital reference multimeter is more accurate for the resistance values 1, 10, 100 Ω, and 1 kΩ. For the values 10 and 100 kΩ; measurement results are very near by using the DC direct and ratio methods. At 100 kΩ; representation of the resistance as an equivalent series resistance is not suitable at frequencies above 10 kHz, while for 100 mΩ and 1 Ω; the equivalent parallel representation is not suitable above the same frequency. The uncertainty analysis is also studied for all the obtained results.     

一种测量氦氖激光器功率的新方法

介绍利用照度计测量氦氖激光器功率的新方法。     

A Vacuum-Free Method for Producing Cubic Titanium Carbide in the Plasma of Low-Voltage Direct-Current Arc Discharge

Technical Physics Letters - The results of a study on the production of cubic titanium carbide in direct-current arc discharge plasma initiated in open air are presented. A feature of the method is...     

电弧法制备碳包覆金属纳米微粒的研究进展

碳包覆金属纳米微粒既可以避免金属纳米微粒的氧化,又能保持其同有性能小变,其潜在科研和应用价值引起了研究者的广泛关注.本文介绍了电弧法制备碳包覆金属纳米微粒的原理,综合评述了碳包覆金属纳米微粒的电弧法制备技术的国内外研究现状,讨论了金属与碳作用后的反应路径,产物类型以及碳包覆金属纳米微粒的形成机理.     

用电位差计法检定直流测温电桥的数据处理方法

直流测温电桥检定规程中用电位差计方法检定测温电桥的数据处理方法不是很详细 ,容易引起歧义 ,有些检定员的数据处理方法甚至会得到不正确的结论。本文针对该数据处理方法谈谈自己的看法     

基于交流测量法的蓄电池内阻测量装置的研究

对传统的几种蓄电池单体电池内阻测量方法如密度法、开路电压法和直流放电法进行了比较分析 ,指出了它们的优缺点。提出了一种新的蓄电池单体电池内阻测量装置 ,该装置以MC6 8332单片机为控制核心 ,采用交流测量法 ,实现了蓄电池单体电池内阻的在线测量。着重介绍了该装置的工作原理以及硬件与软件设计     

New Method of Measuring the Discharge and Quantity of One-Phase Media with Measurement Systems Containing Constrictors

The prospects for widening the range of application of variable-pressure-gradient flowmeters with constrictors are analyzed. That range narrowed appreciably with the promulgation of the standards GOST 8.563.1–97 and GOST 8.563.3–97. It is shown that the range of application of measurement systems with constrictors could be broadened within the limits imposed by RD 50-213–80. The capability of such systems would be enhanced by the use of a new method proposed by VNIIMS to measure the discharge, quantity, and energy content of substances.     

浅谈圆弧半径间接测量的数据处理方法

本文作者提出的数据处理方法大幅度地减少了运算量 ,大大提高了效率。给出的圆度计算公式有明显的几何意义     

The Calibration of DC Resistance Standards by an AC Method

Techniques recently developed at the National Physical Laboratory (NPL) have enabled the zero-frequency (or dc) value of 4-terminal Laboratory Standard Resistors readily to be determined to an accuracy of two parts in 107 from a few measurements made in the frequency band 40 c/s to 600 c/s. A Kelvin double-bridge network is used, the ratio arms consisting of inductively-coupled voltage dividers with an accuracy and discrimination of one part in 107 over the whole frequency range. Experimental results and constructional details of the inductive dividers are given together with the theoretical considerations underlying the principle of the method.     

基于交流放电的UPS电源蓄电池性能测试方法研究

蓄电池性能测试常用直流放电测试方法,所采用的直流放电测试负载对蓄电池的配置数量有一定要求,因而缺乏通用性。利用UPS电源输出交流电的特性,提出了基于交流放电的UPS电源蓄电池性能测试方法。通过详细分析该方法的原理并进行试验,结果表明,该方法适用于不同蓄电池配置情况下的UPS电源蓄电池性能测试,具有较好的经济性和通用性。