铠装热电偶测温的分流误差

Ｋ型铠装热电偶在１０００℃左右的温场中使用时产生的分流误差有时严重地影响其测量准确度。本文介绍：分流误差的量值及分流误差模型；测试条件对分流误差的影响；温度对绝缘电阻的影响和减小分流误差的方法等。     

快速钨铼热电偶的测温误差

文章用热电偶误差计算的通用方法（极限误差表达法），分析了构成快速钨铼热电偶测温误差的因素，从量的角度探讨了各因素对总的误差的影响，对如何认识快速钨铼热电偶的测温精度，提出了可供参考的观点。     

快速钨铼热电偶的测温误差

本文用热电偶误差计算的通用方法（极限误差表达法）分析了构成快速钨铼热电偶测温误差的因素，从量的角度探讨了各因素对总的误差的影响，对如何认识快速钨铼热电偶的测温精度，提出了可供参考的观点。     

热电偶测量误差及其注意事项

热电偶是一种最简单、最普通的温度传感器。可是如果在使用中不注意,也会引起较大测量误差。针对当前出现的问题,详细探讨影响测量误差的主要因素:热电偶插入深度、响应时间、热辐射及热抗阻等,指出热电偶丝不均质、铠装热电偶分流误差、K型热电偶的选择性氧化、K状态、使用气氛、绝缘电阻及热电偶劣化等在使用中应注意事项。对提高测量精度,延长热电偶使用寿命,有一定帮助。     

测温系统组合误差的分析

一、常用测温系统误差的评定方法在热电偶测温系统中,测温的准确度,通常是以二次仪表的精度等级和测量范围为依据的。当测温系统在正常工作时,被测介质的温度,由二次仪表直接显示。热电偶测温系统由相同分度号的热电偶、补偿导线和二次仪表组成,因此测温系统组合误差的大小应由三方面的因素所决定。如果在测温中,不考虑热电偶、补偿导线的误差对测温系统组合误差和测温准确度的影响,而仅以     

热电偶检定系统的误差来源及不确定度的评定

热电偶是热处理过程中主要的测温传感器之．热电偶检定系统是确保热电偶符合国家标准的重要设备：因此,热电偶检定系统的不确定度直接关系到热处理工艺执行的可靠性。本文主要分析了热电偶检定系统的误差来源．并对各个误差的不确定度和整个系统的总不确定度进行了评定。     

一种用于低温下瞬态测温的薄膜热偶技术

薄膜热电偶是采用高真空下离子溅射法制成的。从理论上对它的响应时间常数及动态测温误差进行了分析,并附有初步实验结果。从理论分析和实验结果看来,薄膜热电偶在低温下的响应要快于一般结点型热电偶。     

带电细丝温度测量误差分析

在用热电偶测量带电细丝温度时，影响测量精度的一个主要原因是由于沿热偶丝热量传导而引起的导热误差。本文对该导热误差进行了详细理论推导，分析了影响导热误差的因素。结果表明，为减小导热误差，提高测量精度，须在保证其机械强度的前提下，尽量选用细热电偶丝作为测量工具。     

廉金属热电偶示值误差的不确定度评定

JJG351—1996《廉金属热电偶检定规程》,通过分析计算检定中对热电偶示值误差有影响的各分量的值,并进行有效合成,详细阐述了热电偶示值误差测量不确定度的评定过程和方法。     

测温系统分度号不一致带来的误差

本文通过对测温系统的误差分析，讨论了热电偶、热电阻和温度指示仪表（以下简称仪表）的分度号不一致带来的误差，强调了对它们进行检定的重要性。     

In Situ Thermocouples in Macro-Components Fabricated Using SALD and SALDVI Techniques. III. Fabrication and Properties of the SiC/C Thermocouple Device

Fabrication of a SiC/C thermocouple embedded in an arbitrarily-shaped SiC macro-component has been demonstrated using an integrated Selective Area Laser Deposition (SALD) with the closely related Selective Area Laser Deposition Vapor Infiltration (SALDVI) process. SALD is used to make the embedded thermocouple devices in situ and SALDVI to fabricate the macro-components. The thermocouple elements, silicon carbide and carbon lines, and the electrical insulation layer, Si₃N₄, have been deposited from tetramethylsilane (TMS), acetylene, and a gas mixture of TMS and ammonia, respectively. It is found that the fabricated in situ thermocouples respond sensitively to temperature variation. Furthermore, the electric signal of the embedded thermocouple is very stable and reproducible in response to thermal cycling. This is not the case when the thermocouple is not embedded in the SiC matrix because of the oxidation of the thermocouple elements.     

Linearization and stabilization of the conversion characteristics of a thermoelectric thermometer

An analysis is given of the condition of a digital thermometer utilizing thermoelectric converters (thermocouples). A method is established for digitally correcting the errors due to nonlinearity and instability of the calibration characteristic of a thermocouple by providing additional heating and cooling of its working end by passing calibrated electric current pulses through it. A microprocessor is used to process the effects on the thermocouple of the additional current, without dismantling it from its operating location, in order to correct the errors of the thermoelectric thermometer. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 42–46, May, 1996.     

Quasi-synchronous sampling algorithm and its applications

Synchronous sampling is a commonly used method with good performance. However, when perfect synchronization is impossible, or when the signal contains interharmonics, undesirable asynchronous deviations between the sampling and some components of the signal may exist. Consequently, possibly large leakage or truncation errors may occur. Consisting of a quasi-synchronous window to reduce the long-range leakage, and a compensation algorithm to reduce the short-range leakage after normal FFT, the method described in this paper will give much more accurate measurement of many electrical quantities, e.g., spectral content of signal and phase difference between two periodic signals in power networks, than the traditional one     

Evaluation of Flat Surface Temperature Probes

The objective of this paper is elaboration of elements related to metrological analysis in the field of surface temperature measurement. Surface temperature measurements are applicable in many fields. As examples, safety testing of electrical appliances and a pharmaceutical production line represent case studies for surface temperature measurements. In both cases correctness of the result of the surface temperature has an influence on final product safety and quality and thus conformity with specifications. This paper deals with the differences of flat surface temperature probes in measuring the surface temperature. For the purpose of safety testing of electrical appliances, surface temperature measurements are very important for safety of the user. General requirements are presented in European standards, which support requirements in European directives, e.g., European Low Voltage Directive 2006/95/EC and pharmaceutical requirements, which are introduced in official state legislation. This paper introduces a comparison of temperature measurements of an attached thermocouple on the measured surface and measurement with flat surface temperature probes. As a heat generator, a so called temperature artifact is used. It consists of an aluminum plate with an incorporated electrical heating element with very good temperature stability in the central part. The probes and thermocouple were applied with different forces to the surface in horizontal and vertical positions. The reference temperature was measured by a J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in the European standard EN 60335-2-9/A12, one with a fine-wire (0.2 mm) thermocouple and one with 0.5mm of thermocouple wire diameter. Additional commercially available probes were compared. Differences between probes due to thermal conditions caused by application of the probe were found. Therefore, it can happen that measurements are performed with improper equipment or in an improper way for a particular application. Therefore, knowledge and awareness regarding all facts related to the used measuring equipment are essential to avoid the risk of a wrong decision on safety measures.     

Local temperature measurements on nanoscale materials using a movable nanothermocouple assembled in a transmission electron microscope

A nanoscale thermocouple consisting of merged Cu and Cu-Ni tips is developed for local temperature measurements on advanced nanomaterials by using a probing technique in a high-resolution transmission electron microscope (TEM) equipped with a double probe scanning tunneling microcopy (STM) unit. The fabricated nanothermocouple works as the so-called T-type thermocouple and displays a quick response and high spatial and thermal resolutions. A generated thermoelectromotive force which reflects rapid temperature changes controlled by electron beam intensity alternations on a metal nanoelectrode proves the technique's usefulness for high-precision local temperature measurements. The developed method demonstrates the effectiveness while also measuring temperature changes in Joule heated multi-walled carbon nanotubes (CNTs) and in a modeled electrical conductive composite nanosystem.     

Wolfson淬火测试探头内热电偶动态响应误差的数值模拟

本文采用逼真的三维非均质传热模型及一种改进的交替方向隐式求解方法，对标准Wolfson淬火测试探头中热电偶测温的动态响应误差进行了数值模拟．     

小波变换电力谐波功率测量误差分析与抗泄漏算法研究

通过理论分析指出,在信号非同步采样条件下,基于小波变换的谐波功率测量方法存在着很大的带内泄漏.仿真表明,带内能量泄漏引起的测量误差可达5×10~(-2).针对该泄漏误差,推导了误差公式,并提出了一种基于整系数交迭窗函数的抗带内泄漏的小波变换谐波功率测量新算法.结果可知:抗带内泄漏功率测量新算法的相对误差小于1.2×10~(-4),测量准确度比传统的小波变换谐波功率测量算法提高了两个数量级.     

Specific heat and electrical resistivity of niobium measured by subsecond calorimetric technique

This paper presents results of measurements of specific heat and electrical resistivity of niobium from ambient temperature to the experimental limit of the equipment which is close to 2500 K. The study used a contact thermometry variant of the millisecond resolution pulse calorimetry developed at the Institute of Nuclear Sciences VINA. In the experiments exceeding 1000 K, thermocouple thermometry was supplemented with parallel pyrometric temperature measurements. This, together with application of tungsten; rhenium thermocouple thermometry, increased the temperature range of measurements to 2500 K. In the range where two thermometries overlap, data on the specimen emittance were also generated. Novelties in the method, the results on electrical resistivity. specific heat, hemispherical total emittance and normal spectral emittance of niobium, and accuracies attained in different property measurements are discussed.     

Cryogenic detection of particles with a SQUID-assisted thermocouple Au:Fe-Nb and silicon absorber

The feasibility of thermoelectric detection in cryogenic detectors was demonstrate at elevated temperature of 1 K with a 33 mm³ volume silicon absorber placed in electrical field. Au:Fe-Nb thermocouple was used as a thermometer, installed directly on the heat absorber. The resolution, provided by Au:Fe-Nb thermocouple with SQUID read-out was 2.10^–7 K/Hz^1/2, which is one order of magnitude less than expected, and was limited by a noise of SQUID electronics.     

离散傅立叶变换误差对声强测量技术的影响

离散傅立叶变换(DFT)存在误差。分析DFT泄露误差对声强测量的影响,进行模拟计算。计算结果表明:DFT泄漏误差将引起声强的泄露,在多个频率情况下还可能导致出现不合理的负声强。继而进行实验实测,实测结果与理论分析结论相同。