Reconstruction of Polyhalite Ore-Formed Temperature from Late Middle Pleistocene Brine Temperature Research in Kunteyi Playa, Western China

Kunteyi Salt Lake (KSL), located in the northwest of the Qaidam Basin (QB), is rich in polyhalite resources. However, there is no relevant research on the ore-formed temperature of polyhalite in nature, such as KSL. The homogenization temperature ( T h ) of salt mineral inclusions can directly reveal the form temperature of minerals. In view of the poor diagenesis of polyhalite in KSL, almost no polyhalite crystals are formed. Therefore, the ore-formed temperature of polyhalite in KSL is revealed by using the T h of fluid inclusions in halite associated with polyhalite as a substitute index. A total of 472 T h data from 34 halite samples and 34 maximum homogenization temperature ( T hMAX ) data ranged from 17.1°C to 35.5°C, among which 24 data were concentrated at 17-23°C and the average value is 22.1°C. Brine temperature of other salt lakes in QB and paleoclimate characteristics of the study area were combined. It suggests that the temperature conditions of polyhalite mineralization in the study area are generally low. However, under the overall low-temperature background, polyhalite seems to be easily enriched at relatively high temperature; for example, the content of polyhalite is generally high in the first relatively dry and hot salt-forming period, and the brine temperature at the peak stage of polyhalite at 45 m is relatively high, which indicates that the high temperature conditions promote the formation of polyhalite in KSL. As far as the overall relationship between temperature and polyhalite is concerned, polyhalite is deposited at both low temperature and relatively high temperature, which verifies the previous understanding that polyhalite is a mineral with wide temperature phase, and also shows that temperature has a limited effect on polyhalite formation under natural conditions. In addition, combined with the chemical composition of halite fluid inclusions, it is found that the concentration of Mg2+ in nature has an influence on the temperature measurement process. According to the previous experimental research, speculate that the actual temperature of ancient brine and ore-formed temperature of polyhalite in KSL are lower than the measured T h . The confirmation of the influence of Mg2+ on temperature measurement is convenient for more accurate reconstruction of the metallogenic temperature of evaporite such as polyhalite. The research on the ore-formed temperature of KSL polyhalite enriches and perfects the polyhalite mineralization theory and provides theoretical basis for the basic and applied research of polyhalite.

Correlation Between Insulation Resistance and Temperature Measurement Error in Type K and Type N Mineral Insulated, Metal Sheathed Thermocouples

Mineral insulated, metal sheathed (MI) Type K and Type N thermocouples are widely used in industry for process monitoring and control. One factor that limits their accuracy is the dramatic decrease in the insulation resistance at temperatures above about 600 °C which results in temperature measurement errors due to electrical shunting. In this work the insulation resistance of a cohort of representative MI thermocouples was characterised at temperatures up to 1160 °C, with simultaneous measurements of the error in indicated temperature by in situ comparison with a reference Type R thermocouple. Intriguingly, there appears to be a systematic relationship between the insulation resistance and the error in the indicated temperature. At a given temperature, as the insulation resistance decreases, there is a corresponding increasingly negative error in the temperature measurement. Although the measurements have a relatively large uncertainty (up to about 1 °C in temperature error and up to about 10 % in insulation resistance measurement), the trend is apparent at all temperatures above 600 °C, which suggests that it is real. Furthermore, the correlation disappears at temperatures below about 600 °C, which is consistent with the well-established diminution of insulation resistance breakdown effects below that temperature. This raises the intriguing possibility of using the as-new MI thermocouple calibration as an indicator of insulation resistance breakdown: large deviations of the electromotive force (emf) in the negative direction could indicate a correspondingly low insulation resistance.

A novel method for measuring sublingual temperature using conventional non-contact forehead thermometer

Background: Sublingual temperature measurement is a quick and accurate representation of oral temperature and corresponds closely with core temperature. Sub-lingual temperature measurement using non-contact infrared thermometers has not been studied for this purpose and if accurate they would be a reliable and convenient way of recording temperature of a patient very quickly. The aim of the study was to evaluate the utility of recording sublingual temperature using an infrared non-contact thermometer and establish its accuracy by comparing the readings with tympanic thermometer recordings. Methods: This cross-sectional study was carried out in 29 patients (328 paired recordings from sublingual and tympanic sites simultaneously). Subjects were requested to keep their mouth closed for five minutes before recording the temperature. Sublingual recordings were performed for each patient at different times of the day using an infrared thermometer. The infrared thermometer was quickly brought 1cm away from the sublingual part of the tongue and the recordings were then done immediately. Readings were compared with the corresponding tympanic temperature. Results: The non-contact sublingual temperature correlated very closely with tympanic temperature (r=0.86, p<0.001). The mean difference between the infrared sublingual and tympanic temperature was 0.21°C (standard deviation [SD]:0.48°C, 95% confidence interval [CI] of 0.16-0.27). The intra-class correlation co-efficient (ICC) between core and sublingual temperatures was 0.830 (95% CI: 0.794 to 0.861) p<0.001. The sensitivity of sublingual IR (infrared) temperature of 37.65°C was 90% and specificity was 89% for core temperature >38°C. Conclusions: This innovative modification of using the forehead infrared thermometer to measure the sublingual temperature offers an accurate, rapid and non-contact estimation of core temperature.

Raspberry Pi based automatic temperature measurement and logging system for solar thermal purposes

For automatic temperature measuring and logging purposes in solar thermal experiments, a single board computer - Raspberry Pi based and sensor system is proposed. Different data sets are observed for sensors, thermometers, and thermocouples and they are compared. The consistency of the automated temperature measurement system is also verified.