Standard source for skin type clinical thermometers
A portable standard source for skin type clinical thermometers was developed at CMS for fulfilling industrial and medical demands. It contains a modified a high quality blackbody with large size opening aperture which with large heat capacity and high emissivity. The blackbody is surrounded with heaters and the walls provide good heat conduction. In addition; the horizontal type blackbody was also restricting any excessive air convection. The temperature was measured with thermistors which were calibrated according to the International Temperature Scale of 1990 (ITS-90). The blackbody was designed at two fixed temperature points (38 °C and 30 °C). The long term temperature stability of the portable blackbody for two hour at 38 °C is ±0.0007 °C and at 30 °C is ±0.0011 °C which operation ambient temperature was within (22 + 1) °C. The emissivity of the blackbody is designed at 0.95. For converging factor (k) equals to 2, the uncertainties of the whole standard blackbody system, without device-under-test (DUT), at 30 °C and 38 °C are 0.046 °C and 0.059 °C, respectively, which were also traceable to ITS-90.
A low-temperature blackbody reference source to C
A blackbody reference source has been developed and constructed using a specially designed ammonia heat pipe cavity. This is a high emissivity (0.9993) source which provides radiance temperatures in the range to with a best measurement capability of . The design and construction of this source is presented with the results of stability, temperature uniformity and intercomparison measurements.
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.