Effect of bushings in thermometric fixed-point cells

Bushings are tubular inserts that can be used with temperature fixed-point cells for the calibration of standard platinum resistance thermometers in accordance with the International Temperature Scale of 1990. They are made out of different materials such as glass and various metals with high thermal conductivities. Their function is to increase the thermal contact between the thermometer’s sensor and the phase boundary in the thermometer well of the cell. In the paper, the effect of bushings on the self-heating and on the immersion profiles of thermometers in fixed-point cells was researched. Three different thermometers were used: one fused silica sheathed and two Inconel sheathed. The self-heating was measured in the temperature range from the mercury triple-point to the zinc freezing-point with and without metal bushings: brass, aluminum and copper. The immersion profiles were measured in the zinc cell with and without an aluminum and a glass bushing. Besides experimental measurements, some qualitative results of numerical modeling are also presented. The bushings considerably lower the self-heating, in some cases even by more than 50%. But, on the other hand, bushings seem to increase the measured temperature, worsen the immersion profile and act as a radiation shield in the gap between the thermometer and the fixed-point cell at higher temperatures, where radiation is the dominant mode of heat transfer.     

Comparison of the radiation temperature scales between MIKES and PTB

The radiation temperature scales of PTB and MIKES were compared in the range of 1570–2770 K using four filter radiometers of MIKES, one filter radiometer of PTB, and linear radiation thermometers of both MIKES and PTB. The agreement was partial: two filter radiometers and the linear radiation thermometer of MIKES agreed well with the equipment of PTB, while two filter radiometers deviated from the other equipment. To get a deeper understanding of the reasons of the deviation, the results were studied in terms of both temperature and radiance. The deviation was found constant in terms of radiance. A correction factor was calculated for the radiance level with help of a temperature fixed-point calibration. The use of the correction factor improved the results.     

U 型缺口小冲杆试验评价材料的各向异性

利用开U型缺口小冲杆试样对各向异性材料的轴向、周向和径向三个方向进行了不同温度试验研究,通过小冲杆能量随温度的变化,确定出小冲杆试验的转变温度TSP。结果表明,开U型直线槽小冲杆试验可以表征各向异性材料不同方向的韧脆转变温度及上平台冲击功之间的区别。结合常规小冲杆试验（不开缺口）,得到开U型缺口的小冲杆试验能够更有效地应用于评价各向异性材料的力学性能。     

基于LS-SVM的机械式温度仪表误差预测研究

机械式温度仪表在测量过程中易受到环境温度、毛细管长度以及内部机构影响而出现测量精度不高、非线性的情况,针对这些问题以液体压力式温度仪表作为研究对象,提出了基于最小二乘支持向量机(LS-SVM)的温度误差建模预测的方法。通过分析液体压力式温度仪表的测温结构和误差影响因素,将环境温度及毛细管长度等特征参数作为模型输入,将误差值及误差随毛细管长度的变化率作为输出。根据回归预测的原理,利用网格搜索和交叉验证的方法寻找最优参数组合,建立液体压力式温度仪表的误差预测模型。实验结果表明,该模型可以有效地描述温度误差,并将此建模方法与常用的支持向量机回归建模方法进行比较,基于LS-SVM得到的误差预测模型精度较高、推广能力强,可以对机械式温度仪表进行补偿,为探索机械式温度仪表自适应补偿机构提供理论依据。     

基于超声波的插入式钢水温度测量装置设计

根据超声波在棒状固体介质中的传播速度与该介质温度的关系,设计了一种基于超声波的插入式钢水温度测量装置,该装置能够实现对钢水温度的实时连续测量。感温导杆设计成棒状结构,不仅方便插入钢水测量其温度,而且简化了温度测量原理。采用高速高分辨率硬件电路和软件细分插补算法,可以精确确定超声波回波传播的终点时刻,得到精确的超声波传播时间并计算出对应的温度值。该温度测量装置可以灵活地应用于各种高温环境的温度测量和涉温控制领域。     

THI-700L红外温度计的通信协议分析及自动测量系统的构建

THI-700L是一款非接触式红外温度计,其带有PC端的控制软件,但是,由于该软件不能进行二次开发,给应用带来了不便。文章对温度计与附属软件间通信协议进行了分析,同时介绍了基于LabVIEW的控制软件的设计与实现。该软件实现了被测物体温度的多种显示方式与警告报错及数据存储等功能,解决了原附属软件不能集成到其他测控系统中的问题。实验表明,所设计软件可正确显示温度计的测量结果。     

Optimization of the Probe Design for Nuclear Quadrupole Resonance Thermometry

A continuous-flow thermostat design for a nuclear quadrupole resonance thermometer probe is described. This design makes it possible to significantly decrease the length of the coaxial line connecting the inductance coil to the autodyne and to increase the signal-to-noise ratio. The thermostatting range of the working substance of the probe is 200–500 K. As a working substance of the nuclear quadrupole resonance thermometer, a powder of cuprous oxide (Cu₂O) was used. The temperature measurement accuracy is 0.1 K.     

Variable temperature UHV dual-range cell for spectroscopic surface studies

A stainless steel cell for transmission spectroscopy of surface compounds is described. This cell allows subsequent spectra recording of the sample in two spectral regions requiring different window materials. The sample temperature can be varied from 100 to 700 K, the pressure from 10(-6) to 10(5) Pa. The mean temperatue is measured inside the wafer with a thin platinum wire as a resistance thermometer.     

用不同方法测定材料的玻璃化转变温度

玻璃化转变温度是材料的重要特性参数 ,对材料的研究有着重要意义。测定材料玻璃化转变温度的方法很多 ,各种方法由于其测试条件和测试内容不同 ,结果也各不相同。为更好的了解各种测试方法 ,本文用不同方法对同种样品的玻璃化转变温度进行测定 ,并对其结果进行讨论。     

Tribological Properties of Organic Functionalized ZrB<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/Epoxy Composites

The tribological behaviors of epoxy composites filled with organic functionalized ZrB₂–Al₂O₃ were environmentally investigated and compared with those with as-received fillers under both dry and oil sliding conditions in this work. The worn surfaces and the transfer films on the counterparts were characterized by scanning electronic microscope (SEM), and the frictional temperature rising was investigated by infrared thermometer. The results demonstrated that the coefficient of friction (CoF), the wear rate, as well as the frictional temperature rise of the epoxy composites were all decreased due to the introduction of ZrB₂–Al₂O₃ fillers. And with the increase in filler content, similar variation tendencies of CoF and wear rate of epoxy composites were observed under the different sliding conditions. Besides, the organic functionalization of ZrB₂–Al₂O₃ fillers, which made the epoxy composites exhibit lower CoF and wear rate than those with as-received fillers, lowered the frictional temperature as well. In comparison, the epoxy composites filled with 5 vol% modified fillers presented better tribological properties, suggesting a stronger interfacial bonding between modified fillers and epoxy matrix. The dominant wear mechanisms of filled composites under dry and oil sliding conditions could be inferred as the combination of adhesive wear and abrasive wear and the fatigue wear, respectively, on the basis of SEM images of worn surfaces.     

功能性微结构可控参数建模技术研究

针对多孔结构功能一体化材料设计困难的问题,提出了一种由复合函数驱动的大规模微结构自动化建模技术。通过函数驱动生成三组平行于三轴方向的微结构基本单元,并借助集合论定义的交、并集操作对其进行组合,通过对生成的规则微结构进行仿射、弯曲算子操作,能使其获得一定的复杂曲面适形效果。对胞元节点处形成的自然圆角过渡进行了分析,相对于直接过渡、球体过渡这两种节点处理方式,自然圆角过渡的胞元力学性能分别提高了43.6%和27.9%。将3个变阶数圆形截面微结构填充于旋翼截面模型内部,通过计算3个变阶数旋翼模型在指定的10个采样点处的刚度值以得到模型的节点刚度曲线,研究结果表明：通过调控微结构的分布阶数可以改变模型的刚度分布。     

Narrow band radiative solutions within a cubical enclosure filled with real gas mixtures

Radiative transfer by nongray gas mixtures with nonuniform concentration and temperature profiles is studied by using the statistical narrow-band model and the ray-tracing method with the sufficiently accurate T₆₀ quadrature set. Transmittances through the nonhomogeneous gas mixtures are calculated by using the Curtis-Godson approximation. Three different cases with different temperature and concentration profiles are considered to obtain benchmark solutions for the radiative transfer by nongray gas mixtures. The solutions obtained from this study are verified and found to be very well matched with the previous solutions for uniform gas mixtures. The results presented in this paper can be used as benchmark solutions in developing various solution methods for radiative transfer by nongray gas mixtures.     

Measurement of the properties of liquids and gases using a transient hot-wire technique

A transient method of making simultaneous, in situ measurements of the thermal conductivity, volumetric specific heat, and kinematic viscosity of liquids and gases is presented. The technique utilizes the temperature response record of a fine horizontal wire, functioning as a resistance thermometer, when subjected to a sudden and constant electrical heating. It is shown that a formulation of the transient mechanisms governing the transition from pure conductive to free convective heat transfer from the wire can be used to produce simultaneous determinations of fluid properties from a single wire temperature versus time record. A simple apparatus is presented, along with the results of its use in determining the properties of air.     

An optical high-pressure cell for transient grating measurements of biological substance with a high reproducibility

We describe a high-pressure optical cell that can be used for time-resolved transient grating measurements to determine the thermodynamic properties of transient species under high pressure. This high-pressure cell enables us to compare the grating signal intensities of different samples quantitatively. Using this high-pressure cell with an inner sample cell, one can measure various thermodynamic properties of a biological substance in time domain. The stability and reproducibility of this apparatus are described.     

New radiation thermometer for near room temperature

The authors have developed a new radiation thermometer for the measurement of near room temperature with high signal-to-noise ratio (S/N). The thermometer, utilizing an HgCdTe semiconductor sensor, is compact and insensitive to temperature changes of the surroundings. Its major breakthrough owes much to the fact that the sensor is cooled and controlled by Peltier thermoelectric devices and that the sensor serves as reference radiator. A well designed optical system with a chopper and a concave mirror shuts off stray radiation, thus improving the S/N.

On-line experiments in a steel sheet manufacturing process using a prototype thermometer proved the validity of this new radiation thermometer.     

Infra-red temperature measurement of bright metal strip using multiple reflection in a roll-strip wedge to enhance emissivity

In a continuous annealing furnace, strip temperature was measured using radiation thermometers aimed, at a shallow angle to the strip, into the wedge-shaped cavity formed between the strip and a roll. The dependence of the observed temperature on thermometer operating wavelength, field-of-view, aiming and polarisation was investigated. Comparison was made against reference temperatures taken with a surface pyrometer and also derived from strip metallurgy. Control of the furnace, using a wedge thermometer, was demonstrated. The technique is potentially applicable in a wide variety of bright metal processing furnaces.     

Differential membrane-based nanocalorimeter for high-resolution measurements of low-temperature specific heat

A differential, membrane-based nanocalorimeter for general specific heat studies of very small samples, ranging from 0.5 mg to sub-μg in mass, is described. The calorimeter operates over the temperature range from above room temperature down to 0.5 K. It consists of a pair of cells, each of which is a stack of heaters and thermometer in the center of a silicon nitride membrane, in total giving a background heat capacity less than 100 nJ/K at 300 K, decreasing to 10 pJ/K at 1 K. The device has several distinctive features: (i) The resistive thermometer, made of a Ge(1 - x)Au(x) alloy, displays a high dimensionless sensitivity ∣dlnR∕dlnT∣ ? 1 over the entire temperature range. (ii) The sample is placed in direct contact with the thermometer, which is allowed to self-heat. The thermometer can thus be operated at high dc current to increase the resolution. (iii) Data are acquired with a set of eight synchronized lock-in amplifiers measuring dc, 1st and 2nd harmonic signals of heaters and thermometer. This gives high resolution and allows continuous output adjustments without additional noise. (iv) Absolute accuracy is achieved via a variable-frequency-fixed-phase technique in which the measurement frequency is automatically adjusted during the measurements to account for the temperature variation of the sample heat capacity and the device thermal conductance. The performance of the calorimeter is illustrated by studying the heat capacity of a small Au sample and the specific heat of a 2.6?μg piece of superconducting Pb in various magnetic fields.     

半导体温度传感器在直升飞机测温上的应用

半导体温度传感器具有较高的精度和良好的线性输出。采用LM135型半导体温度传感器,与CPU、数码管接口,经A/D和V/F转换等信号处理,成功研制了某直升飞机数字大气温度显示器,取代了双金属片指针式温度计。试验结果表明LM135传感器在-55℃～70℃可以实现单点校准,在-60℃～-55℃出现非线性,可以通过程序进行单点补偿校准。     

GENERAL PROCEDURE FOR UNCERTAINTY EVALUATION OF A TEMPERATURE CALIBRATION BATH

ABSTRACT

The objective of this paper is to develop a general procedure for evaluation of various temperature calibration baths or furnaces. Since the uncertainties of transfer measurement and temperature standards, such as standard platinum resistant thermometers in particular, are decreasing, metrological characteristics of calibration baths and furnaces are becoming a limiting factor in temperature calibration by comparison. Due to the fact that a time invariance of metrological characteristics of calibration baths (gradients, stability, repeatability, etc.) represents a major contribution to the total calibration uncertainty, the exact knowledge about a calibration bath is of an utmost importance.

A general procedure for baths with different types of a media is proposed, which enables continuous monitoring of bath parameters in order to evaluate uncertainty contributions to a measured (calibrated) thermometer. There is no ideal calibration system, i.e., without inhomogeneity or gradient. Basic gradients that could be observed in calibration baths are vertical and horizontal gradients. They may also be recognized as axial and radial gradients in a case where cylindrical equalizing blocks are used inside a calibration bath. For the proper use of such a system in a process of calibration and measurement, gradients should be precisely determined.

Gradients appear as a change of a temperature reading of a thermometer due to a change of its position inside a calibration bath. By this method, a realistic uncertainty contribution could be defined as opposed to under-or overestimated values of uncertainties, thus enabling an optimal use of a particular calibration bath. Examples of real data are taken from cryostat measurements. Otherwise, seven other temperature calibration baths and furnaces in the laboratory have been evaluated in the same way.     

半导体温度传感器在直升飞机测温上的应用

半导体温度传感器具有较高的精度和良好的线性输出。采用LM135型半导体温度传感器,与CPU、数码管接口,经A/D和V/F转换等信号处理,成功研制了某直升飞机数字大气温度显示器,取代了双金属片指针式温度计。试验结果表明LM135传感器在-55℃～70℃可以实现单点校准,在-60℃～-55℃出现非线性,可以通过程序进行单点补偿校准。