Scanning iron temperature lidar for mesopause temperature observation

We introduce a new method for temperature profile measurements in the mesopause region in the altitude range from 80 to 105 km. A frequency-doubled narrowband alexandrite laser is used to scan the iron resonance line at 386 nm. The isotopic shifts of the iron isotopes and the laser bandwidth are derived by the measurement itself. Neglecting the minor isotopes results in large temperature errors up to 28 K. We discuss the derived temperatures in comparison with results of our potassium temperature lidar. The iron lidar-derived temperatures have typically a statistical error of 0.4 K and vary by less than 10 K, which is due to the daily natural variation. The all-solid-state system, which is compact, can be containerized and deployed at remote locations.     

Dynamic temperature model and dynamic temperature compensation ofcrystal oscillators

In temperature-compensated crystal oscillators (TCXO), the compensating action is commonly estimated as a function of one variable-environmental temperature, At the same time, experimental data show that TCXO frequency stability is also dependent on the dynamics of the temperature process. The greater the temperature variation, the more pronounced Is the loss of temperature compensation. In this paper, the origins of this phenomenon are analyzed, and a method for reducing its effects is presented. A new approach is suggested according to which the compensating action is formed as a function of two variables: the temperature and the rate of its variation. A theoretical basis for this method is given. A functional model of the devices performing the dynamic temperature compensation is suggested. Experimental investigations of a TCXO with a microprocessor-based dynamic temperature compensation system confirmed the possibility of TCXO frequency stability improvement in nonstationary thermal conditions. In a system using an AT cut resonator and a separate Y-cut thermosensor, the application of dynamic temperature compensation resulted in an order of magnitude improvement as compared to conventional digital temperature compensation procedures. Even with dual-mode SC-cut resonators, the application of dynamic temperature compensation is shown to be useful     

Assessment of failure temperature of ultra-high temperature ceramic plates

A theoretical model is presented to assess the failure temperature for ultra-high temperature ceramics (UHTCs). The parameters in the present work, such as thermal expansion coefficient and Young’s modulus, are considered functions of temperature to calculate the stress field of UHTCs under high temperature conditions. The critical elevated temperature for failure is calculated by using the Maximum Principle Strength theory. By establishing the relation between the temperature and the mechanical properties of the UHTCs, it is found that the failure behavior of UHTCs is affected by initial temperature.     

Assessment of failure temperature of ultra-high temperature ceramic plates

A theoretical model is presented to assess the failure temperature for ultra-high temperature ceramics (UHTCs). The parameters in the present work, such as thermal expansion coefficient and Young’s modulus, are considered functions of temperature to calculate the stress field of UHTCs under high temperature conditions. The critical elevated temperature for failure is calculated by using the Maximum Principle Strength theory. By establishing the relation between the temperature and the mechanical properties of the UHTCs, it is found that the failure behavior of UHTCs is affected by initial temperature.     

液氦温区国际温标的转换

概括介绍液氦温区国际实用温标的发展情况,系统地给出温标T24,T29,T32,T37,TBS,T48,T55E,TL55,T58,T62,T68,T76以及目前正在采用的T90之间的转换关系,为此编写了计算机程序,可直接用于以上各温标间的数值转换.     

Relationship between crystallization temperature and melting temperature in crystalline materials

The ratio of the absolute temperature at which the homogeneous nucleation rate or the crystal growth rate is maximum (T _cmax) to the absolute melting temperature (T _m) is analysed by two parameters: one is the ratio of the activation energy for migration (E) and the heat of fusion (H _m), the other is the ratio of mean molar surface energy and H _m. In analysing the crystallization data for a large number of crystalline materials such as metals and inorganic, organic and polymeric materials, the ratios and E/H _m show roughly constant values for a given type of material. The constancy of the two parameters will then give rise to a constant value ofT _cmax/T _m.     

超高温传感器用感温材料与结构特性分析

针对现有蓝宝石光纤温度传感器测温上限难以突破1 700℃的瓶颈问题,本文分别从传感器测温结构和感温材料两方面进行了分析改进,以满足对2 000~2 500℃超高温的测量需求.提出了一种接触-非接触相结合的新型传感器测温结构,并结合非接触式测温结构特点给出了Plank黑体辐射温度误差补偿公式,解决了非接触结构的准确测温问题.结合不同感温材料特性分别对难熔金属、陶瓷基复合材料和C/C复合材料的高温性能进行分析比较,包括材料强度、密度、抗氧化性、塑性、熔点等,筛选出适合作为超高温传感器的备选感温材料.针对筛选出的感温材料设计了抗热震性试验和抗氧化烧蚀试验,实验结果表明Hf B2-Si C复合材料能够满足超高温环境下对感温材料物理特性的特殊需求.传感器温度试验结果表明,采用接触-非接触式新结构和Hf B2-Si C感温材料的新型光纤温度传感器可对2 500℃高温进行长时间稳定测量,测量精度达到±1%.     

Spatial distribution of temperature and temperature instability of a thermoelement

We show that, depending on the spatial distribution of temperature in semiconducting thermoelements, both "negative" (onset of temperature instability at negative temperature differences) and "positive" temperature instabilities may set in. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 3, pp. 542–543, May–June, 1998.     

液体化学品自燃温度试验中温度控制器性能仿真

GB/T 21860-2008(液体化学品自燃温度的试验方法)是液体化学品自燃温度测定方法的标准,若采用常规PID(比例、积分、微分)温度控制存在超调会影响试验结果精确度.根据坩埚炉低温区间升温速度快、高温区间升温速度慢的特点,以及国家标准中要求以30℃和3℃进行温度调节,对坩埚炉当前温度和所需调节温度两个变量进行模糊化处理,建立此坩埚炉的模糊控制规则库,构造坩埚炉温度的模糊PID控制器.在仿真情况下,模糊PID控制没有超调,控温精度达到目前国外产品同等水平.模糊PID控制器的设计,为实际试验过程中的坩埚炉温度控制器设计积累了经验,寻找到了方向.     

Digital temperature regulator

This article examines a digital temperature regulator for the 0–1250°C range. The regulator has an error amounting to ±0.3% of this range. It has a four-sided double circuit board construction with a common bus. The static characteristic of the thermcouple of the unit is linearized. Control points are stored in nonvolatile memory. The unit provides for positional and PID regulation, generates a signal if the thermocouple fails, and performs other functions. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 35–38, November, 1996.     

High temperature technology

An attempt has been made to outline the areas where progress in various aspects of high temperature technology would produce significant industrial advantages. The aspects covered range from the possibilities of using the heat lost by conventional industries through to areas of newer technologies, such as fusion reactors and magnetohydrodynamic power generation, where a breakthrough in high temperature technology would encourage their useas viable commercial systems. The advantages of increased temperatures for greater efficiencies and the possibilities of using lower grade or alternate fuels are discussed together with the problems posed both in materials terms and in terms of the technical limitations of process control.     

Low temperature calorimeters

Properties of calorimetric detectors at low temperatures are discussed. Superconductors at the critical temperature used as thermometers and superconducting tunnel junctions are considered as sensors for energy absorption. The different mechanisms of detection are compared and eventually achievable sensitivities estimated.     

Unsteady temperature discontinuity

The condition of an unsteady temperature discontinuity is derived for a one-dimensional heat flux in a gas at rest.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No. 2, pp. 357–358, August, 1971.     

盲孔测温传感器瞬态温度测试研究

目前炮膛内壁瞬态温度具有温度高、变化快、测试环境恶劣等特点,不便于准确测量,普遍采用动态校准方法来减少瞬态温度的误差,但是该方法对仪器动态性能要求高。该文根据测试系统原理,利用盲孔测温传感器验证炮膛内壁瞬态温度的变化,采用非接触式测量瞬态温度,同时利用分析法外推技术对0.05 cm和0.1 cm处的温度进行推导。实验表明:在误差允许的范围内,0.05 cm和0.1 cm处的温度与实验测得的温度变化一致。论证该系统对炮膛内壁瞬态温度测量的可行性,可以完成在恶劣环境下的数据测量,并且该系统成本低,数据可靠,结构简单,对今后更加深入地研究膛内壁瞬态温度有参考价值。