锅炉水溶解固形物测定结果的不确定度评定

测量不确定度是一个与测量结果相联系的参数,表征合理的赋予被测量之值的分散性[1]。测量结果的可用性很大程度上取决于其测量不确定度的大小。测量结果表述必须同时包含被测量的值及与该值相关的测量不确定度才是完整并有意义的。本文根据GB/T1576-2008[2]中测定溶解固形物的第一种方法,分析计算了这种方法检测结果的不确定度。     

钢丝拉伸强度试验结果不确定度的评定

任何检测都存在误差,不确定度是了解测量值可靠程度的途径。在钢丝拉伸强度试验中,测量过程引入的不确定度的主要来源有测量的重复性和仪器校准的不确定度,运用统计学公式合成检测结果的扩展不确定度。     

石墨炉原子吸收法测定水中铅的不确定度

测量不确定度是合理地赋予被测量之值的分散性,与测量结果相联系的参数.检验结果的准确性和可靠性在很大程度上取决于其不确定度的大小,因此,合理评定测量结果的不确定度是分析实验室必须重视的问题.文章通过大量的实验和数据统计,对石墨炉原子吸收法测定水中铅的不确定度的来源以及量化等进行了探讨,旨在交流,规范水质检测中的测量不确定度的评定.     

低分子聚酰胺树脂胺值测量不确定度的评定

根据不确定度评定的通用规则,分析了低分子聚酰胺树脂胺值测量不确定度的主要来源,并对各个因素逐项评估.结果表明,测量重复性对低分子聚酰胺树脂胺值测量结果的不确定度影响最大,因此,在试验过程中,要提高操作的准确性,减少测量仪器的变动性     

球度误差评定的网格容差确定

采用人工智能算法依照最小区域法评定球度时,终止条件存在过度迭代和迭代不足问题。依据不确定度传递公式和误差可以忽略的条件推导得:球度评定时球心坐标的不确定度小于0.47倍测量不确定度时可以忽略。逼近程度小于这个值后,继续逼近是没有意义的。通过对网格算法评定球面度中网格容差的确定验证了该结论有效性。结论作为智能评定球度时的终止条件,比传统的以迭代次数和迭代时间、适应度限作为结束条件更为科学、合理。     

汽车制冷压缩机电磁离合器绕组温升不确定度评定

本文通过对4A-GEU平台车型汽车制冷压缩机电磁离合器线圈进行绕组温升测量,利用A类和B类测量不确定度评估方法,对绕组温升测量过程产生的不确定度各个分量进行了评定,并且分析了汽车制冷压缩机电磁离合器线圈绕组温升测量不确定度主要影响因素。本次试验选用最典型的试验对象,并进行系统的不确定度分析,对汽车制冷压缩机电磁离合器线圈绕组温升试验的教学具有重要的指导意义。     

砝码真空质量值测量结果的不确定度评定

本文以全国砝码质量参数倍量、分量计量比对项目为实例,论述了砝码真空质量值测量结果不确定度的评定方法。对砝码真空质量值的测量方法进行概述,建立数学模型,实际测量被检砝码。对影响测量结果的不确定度来源进行分析,采用了A类评定和B类评定两种不确定度评定方法计算标准不确定度分量;给出合成标准不确定度、扩展不确定度及报告。     

车载充电机输出电流误差试验测量不确定度评定

考虑CNAS对测量不确定度的重视,以及测量不确定度对测量、试验结果的影响,结合电动汽车非车载充电机输出电流误差试验,采用分析测量过程、建立测量模型、确定合成标准不确定度表达式、评定不确定度分量、计算合成标准不确定度数值、评定扩展不确定度和报告测量结果的七步骤法评定测量不确定度,使测量不确定度评定简便易懂,有助于检测实验室实施CNAS-CL01:2018《检测和校准实验室能力认可准则》有关"测量不确定度评定"的要求。     

不确定度在链长精度测量中的应用

一个完整的测量结果应包含测量不确定度,测量不确定度的大小决定了测试结果的可信程度。对于不同产品和测试方法,影响测量不确定度的因素以及不确定度的计算方法不同。在链条行业链条产品的链长精度测量中首次引入不确定度,通过大量的试验测试和理论分析,找出了影响不确定度的主要因素。在此基础上,根据贝塞尔公式得出计算链长精度不确定度的理论公式,给出了不确定度在报告中的表述方法,讨论了不确定度对测量结果的影响。     

凯氏定氮法测定乳粉中蛋白质的不确定度分析

测量不确定度定义为表征合理地赋予被测量之值的分散性[1]。一个完整的测量结果,除了应该给出被测量的最佳估计值之外,还应同时给出测量结果的不确定度。本文依据凯氏定氮法,对奶粉中的蛋白质含量的不确定度各分量进行计算合成,找出影响不确定度的因素,进行评定。     

Operation simulation of a high-voltage nanosecond multistage generator

A model of a high-voltage nanosecond multistage generator employing series voltage addition in the transmission line with stepwise adjustment of the wave impedance is described. The forming lines are coaxial to the transmission line. The generator contains three arrays of switches which are brought into operation one-by-one with a delay equal to the time in which the electromagnetic wave propagates between them, thus forming across a 2.5-kΩ load a pulse whose amplitude is five times higher than the charge voltage of the forming lines. The calculated generator efficiency on an 8.4-Ω matched load is 95%.     

高压输电导线的损伤检测与故障诊断

本文利用红外和电磁传感器分别检测铝绞线和钢芯（钢绞线）的断股故障信号,应用db4小波基对故障信号进行了小波分析,由故障信号的时频域和小波分解细节特征,构造了神经网络诊断模型的输入特征矢量.利用3层BP网络实现了导线断股故障的精确诊断,所研制的红外电磁检测仪器可由巡线机器人携载和操作.     

Mechanism and modeling of rain-wind induced in-plane vibration on high-voltage transmission line

In the planning of ultra high-voltage transmission lines that crossover southeast regions of China, one of the key questions is the prediction of vibrations in the conditions of a complex terrain, rainfalls and wind. As the presence of raindrops in the wind filed influences the dynamic stability of the transmission line, the objective of this paper is reveal the mechanism of rain-wind induced in-plane vibration by analyzing the effects of time-varying mass of raindrops and the motion of upper rivulet that is suspended to the high-voltage transmission line. A rain-wind induced in-plane vibration model with time-varying mass is proposed base on the finite element method and the central difference method. Applying our method to the Tuo-chang transmission line, we use the finite element method to develop the numerical model of the transmission line movement under the action of wind and corona forces, while time discretization is made with the central difference method. The results show that the time-varying mass of raindrops and moving upper rivulet have obvious effects, and the model enables better comprehension of the rain-wind induced in-plane vibrations of transmission lines.     

电动汽车高压电缆材料及其制备工艺概述

由于环境污染和资源枯竭的双重原因,电动汽车逐渐成为汽车产业的焦点.高压电缆作为电动汽车能源传输系统的纽带,承担着能量传输的作用.根据公司产品的研发生产情况对电动汽车用高压电缆的导体材料、绝缘层材料、屏蔽层材料及其制备工艺两方面进行概述,为电缆厂商的生产和电动汽车应用选型提供参考.     

A Computerized System for Controlling the Wavelength of a High-Power Dye Laser

A system for the rotation of a dispersive laser element with a stepper motor is described. The motor is controlled by a personal computer that can be located at a distance of more than 20 m from the motor. The stepper control unit is connected to the computer interface board by a twin line. The system ensures highly reliable operation under conditions of intense electromagnetic noises from the laser power supply system due to the use of noise-suppressing differential transmission lines and optoelectronic isolators.     

Mechanism and characteristic of rain-induced vibration on high-voltage transmission line

Under the rainy weather, rain-induced vibration on high-voltage (HV) transmission line often occurs, which intensifies fatigue conductors and tower callapses. Mechanism and control measures of the rain-induced vibration have aroused wide attention in power engineering. The mechanism can be explained that the droplets suspended to the conductors amplify corona discharges with ionic wind, forms non-circular cross-sections, and the rain-induced vibration is due to the coupling action of vortex-induced vibration by ionic wind and galloping vibration by external wind force. Based on the mechanism, a valid model on the rain-induced vibration on high-voltage transmission line is proposed based on the finite element theory and the Newmark algorithm. Taking the conductor LGJ-240 as an instance, we investigate the effects of ionic wind and non-circular cross-sections with different parameters on amplitude of the conductors. The result shows non-circular cross-sections have obviously effects, and the ionic wind have a certain influence and easily to coupling with wind force. Mechanism and conclusions in this paper can be used as references to construct High-voltage transmission lines, upgrade the existing lines and control vibration.     

高透光率感性网栅膜的电磁屏蔽

在确保制作感性网栅膜后光学窗红外透射率下降小于5%的前提下,研究了影响感性网栅膜电磁屏蔽特性的主要因素。归纳了感性网栅膜红外透射率公式,运用含阻抗边界条件的谱域Galerkin法推导了周期结构金属网栅的电磁场积分方程,用周期矩量法计算出网栅的反射系数及透射系数,进而求出其电磁屏蔽效能;计算并分析了采用不同线宽、周期、衬底材料、衬底厚度时透明导电光窗(金属网栅膜)的电磁屏蔽效能。最后,采用激光直写、真空镀膜等工艺在ZnS基底上制作了周期为360 μm×360 μm、线宽为12 μm,方块电阻分别为13 Ω、25 Ω的样片,采用自由空间法测试了2~18 GHz频段的电磁屏蔽效能。测试与分析结果表明:当感性网栅膜在8~10 μm波段引起的平均透射率下降小于2%的情况下,电磁屏蔽效能平均达到了20 dB以上。结果显示网栅的光电特性是矛盾的,线宽与周期越小电磁屏蔽效果越好,同时应尽量降低网栅的表面电阻。     

High-voltage pulsed generator for dynamic fragmentation of rocks

A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300?μF) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ～50?ns, current amplitude of ～6?kA with the 40?Ω active load, and ～20?kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday's cage (complete shielding) to exclude external electromagnetic perturbations.     

焊接机器人电弧式传感器抗电磁干扰分析

文中针对焊接机器人工作所处的复杂电磁环境,对其电弧式传感器进行了抗电磁干扰分析。首先结合弧焊机器人的工作原理,探讨了机器人焊接时产生的电磁骚扰源特性,通过骚扰源特性分析了电磁骚扰源中骚扰信号对电弧式传感器的干扰耦合机理;接着根据干扰耦合机理,分别从抑制骚扰源信号传播、切断耦合通道和降低敏感设备的敏感性3 个方面对电弧式传感器进行了抗电磁干扰分析;最后进行了近场串扰耦合仿真分析。分析结果表明,在信号经传输线传输的过程中,若传输线有适宜的终端,电感性近场串扰就会明显降低,电弧式传感器提取信号产生偏差的次数就会减少,从而改善电弧式传感器电磁干扰问题。该研究可为电弧式传感器电磁抗干扰研究提供理论依据。     

High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines

A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.