Radial and longitudinal temperature gradients within cold-seal pressure vessels can contribute significantly to the total temperature unccrtainty in any one experiment and it is important to calibrate such gradients before experiments are undertaken. We have measured temperature gradients in vertically mounted large cold-seal vessels at 1 atm and 1 kbar and in the temperature range 500–800°C Radial gradients were measured with the vessel at various positions within the furnace by recording the temperature difference between a thermocouple in the internal bore of the vessel and one in a well in the top of the vessel. We find that when the vessel is at a certain position in the furnace, the temperatures read by these two thermocouples are equivalent to within 1°C. The contribution of radial gradients to temperature uncertainty can be thus be substantially minimized if experiments are undertaken with the vessel in this position. Longitudinal gradients of 2.8°C/cm at 500°C and 3°C/cm at 800°C were recorded at 1 kbar. These profiles are significantly steeper than those recorded at 1 atm. Not to calibrate temperature gradients at the experimental conditions or failure to calibrate vessels at all could lead to large temperature uncertainties.

MEMS gyroscopes as a kind of angular rate sensor have been widely used, but theiraccuracy tends to be low in practical applications, especially under temperatureinfluence, and they generally require error compensation. Based on the analysis ofgyroscope operating principle, this paper has shown that the resonant frequency andmeasuring precision of the gyroscope are dependent on temperature and temperaturegradients. The paper has thus proposed a compensation model based on temperature andtemperature gradients. The experimental results have demonstrated that the thermal driftof zero bias can be effectively suppressed, and the accuracy can be improved by one orderof magnitude after compensation. Compared with compensation methods only based ontemperature, the new method gives significantly better performance. The new errorcompensation model has not only integrated the differences under different temperatureconditions, but also reduced the repeatability errors. It provides a theoretical basis foraccurate compensation of the gyroscope thermal error in practical applications and isapplicable to other MEMS gyroscopes.