Membership notes

The key feature of non-contact temperature measurement provided by infrared (IR) cameras underpins their versatility. However, the accuracy of temperature measurements with IR cameras depends on imaging quality due to their non-contact nature, such as the lens, body temperature, and measurement environment. This paper addresses the correction of radial distortion and nonlinear response issues in IR cameras. To address radial distortion, we have designed a passive checkerboard calibration board specifically for infrared cameras. This board is used to calibrate the IR camera and derive the necessary camera parameters. Subsequently, these parameters are applied during the actual measurement process to rectify radial distortion effectively. Building on the radial distortion correction method mentioned above, we propose a multi-point segmented calibration approach that considers different temperature ranges and imaging regions. This method alleviates the issue of reduced temperature measurement accuracy due to variations in camera responses by computing gain and offset coefficient matrices for each temperature range. Experimental results demonstrate the effectiveness of the calibration board in correcting radial distortion in IR cameras, with a mean reprojection error of less than 0.16 pixels. Regarding the nonlinear response problem, the introduced method significantly reduces the relative error in temperature measurement. In the verification phase, spanning from 100 to 500 °C, the average relative error in temperature measurement decreases by 0.49% from 1.61% before and after correction, which highlights a substantial improvement in temperature measurement accuracy. This work gives a useful reference to improve the imaging quality and temperature measurement accuracy using infrared cameras.

A new method is proposed for correcting the error of monochromatic method in measuring the surface temperature of turbine blades with the influence of reflection. The measurement error caused by surrounding components were numerically investigated. The effects of background temperature, adjacent rotor blades, front stator vanes and rear stator vanes on the temperature measurement error are described in detail. Furthermore, the corrected errors of high emissivity and low emissivity are compared and analyzed and the influence of the relative displacement between the turbine blade and the hot-end component on the temperature measurement error is also discussed. Benefiting from the proposed radiation-based error correction method (RECM), we can reduce the monochromatic temperature measurement error to less than 0.3 % at high emissivity and less than 0.8% at low emissivity theoretically. Finally, the RECM method is studied experimentally, and the results show that the temperature measurement error can be corrected to better than 0.6%, which is in good agreement with the Monte Carlo simulation results.

Subject of research: the article is devoted to the development of a methodology for express diagnostics of material properties based on the measurement of macrokinetic parameters of the SHS process.
 Purpose of research: plotting the dependence of the microhardness of SHS products on the propagation velocity of the SHS wave and its temperature.
 Methods and objects of research: the research objects were the SHS process in the Ni-Al system and the reaction products; To measure the propagation velocity of a high-temperature synthesis wave, an original method of chrono-topographic analysis of thermal imaging data was used; temperature control was carried out by an original method of spectral-brightness pyrometry. The study of the microhardness of experimental samples was carried out using an FM-800 microhardness tester.
 Main results of research: in the course of experimental studies, it was shown that the error in determining the propagation velocity of the SHS wave by the method of chrono-topographic analysis of thermal imaging data is 0.1 %, and the error in temperature measurement by the method of spectral-brightness pyrometry is estimated at 0.5 %. It is concluded that the main factor influencing the total error in the SHS wave propagation velocity in the experiment is the inaccuracy of setting the charge parameters for a set of samples. The absolute value of the total error was 3.2 %. A diagnostic trajectory has been constructed that makes it possible, based on the SHS propagation rate and reaction temperature, to evaluate the microhardness of the product and draw a conclusion about the quality of charge preparation for the production of a material with desired properties.

There are three major types of errors that can cause a temperature probe to read a value different from the true fluid temperature into which it is immersed. One type is the transient temperature lag error in general purpose temperature sensors. Another is an error due to radiation heat transfer from walls at high temperatures. The other type is the error due to thermal energy conduction in lead wires and/or thermowell or other casing from a base on which the temperature probe is mounted. Although much study has been devoted to the former, very little exists on the latter. In fact, any prior research on this subject assumed that the entire sensor was completely immersed in the fluid, which in many cases is not true. For all of these types of errors, the cause is the misunderstanding that all physical sensor types only measure their own temperature, which may or may not be equal to the fluid temperature into which they are immersed. This article focuses on conduction error in temperature measurements and quantifies in simple terms a temperature error and lays out a general method for backing out (reconstructing) true fluid temperature from the sensor temperature measurement. Although only thermocouples are experimentally tested here, the theoretical work is valid for other types of physical sensors as well. The experimental verification for the model shows very good agreement.

Effect of temperature measurement error on parameters estimation accuracy for thermal response tests

Finite element models of fast-response CO-AX thermocouples typically used for heat transfer measurements in diesel engines have been developed. Due to the small differences in thermal properties between the thermoelements and the iron engine components, CO-AX thermocouples are capable of measuring transient temperatures of iron components within an accuracy of 98 percent. However, these relatively small errors in temperature measurement result in as high as 25 percent errors in peak surface heat flux calculations. This implies that heat flux results depend not only on the temperature of the surface thermocouple junction, but are also sensitive to its time rate of change. Increasing the thin film thickness can significantly alter the heat flux profile deduced from surface junction temperatures.

Effect of axial length and keratometry measurement error on intraocular lens implant power prediction formulas in pediatric patients

Satellite radar altimetry is presently the only method that has provided the spatial coverage and density of observations needed to reduce the present uncertainty in the mass balance of the Greenland Ice Sheet and its contribution to change in eustatic sea level. The only such measurement reported, however, estimated that southern Greenland was thickening at 23±6 cm a-1 which is larger than was thought hitherto. This value is reconsidered given more recent information concerning the errors in the measurement. A survey of measurements of specific mass balance of the Greenland Ice Sheet is given, together with estimates of its sensitivity to temperature change. The expected behaviour is described of errors in the satellite position and errors in the range measurement to the ice sheet surface. The treatment of biases and the number of independent observations of random errors is described. It is found in particular that a higher degree of independence was given to the random errors than should have been the case. The total error is recalculated with this accounted for, and is found to remain dominated by the bias estimate and therefore largely unaffected by this change; the estimate is 23 ± 7 cm a-1. It is concluded that the observation does support a recent thickening of the southern Greenland Ice Sheet.

The reproducibility of 99m Tc-pertechnetate single photon emission computed tomography (SPECT) for measurement of gastric accommodation in healthy humans: Evaluation of the test results performed at the same time and different time of the day (

Model Predictive Control (MPC) has emerged as a potential control architecture for operating buildings in a more energy efficient manner. We study through simulations the effect of several sources of uncertainty that arise in the implementation of MPC on the energy consumption, thermal comfort, and indoor air quality (IAQ). These include occupancy profile, measurement errors and mismatch between the plant and its model that the control algorithm uses. Simulations are carried out for two extreme cases: a winter day with no solar load and a summer day with high solar load. The study shows that increasing fluctuations in occupancy, errors in measuring occupancy, and model mismatch have the strongest impact on the energy consumption. However, measurement errors in outside temperature and solar load does not have significant impact. Therefore, it is possible to improve the controller performance by using more accurate occupancy sensors. Furthermore, implementation cost can also be reduced by eliminating the sensors and prediction algorithms for predicting outside temperature and thermal loads without compromising the controller performance. Even with these uncertainties, MPC delivers 12-37% reduction of energy use over conventional control methods without affecting thermal comfort and IAQ.

The dust generated in industrial processes has a serious impact on the accuracy of infrared thermometry, which is also the main reason for the limited use of infrared temperature measurement methods in industrial applications. To reduce the influence of dust on infrared temperature measurement, this paper proposes a new method for compensating measurement error caused by dust. First, the source of temperature measurement error caused by dust is analyzed, and a compensation method, in which the dust transmittance is important but difficult to determine, is proposed based on the principle of infrared temperature measurement. Then, to solve the difficulty of determining dust transmittance, we define a spatial temperature-level co-occurrence matrix and a neighboring temperature-level dependence matrix that can be utilized to extract the infrared thermal image's texture features affected by dust. Finally, by integrating stacked denoising auto-encoder with optimized parameters and support vector regression, a dust transmittance model is established to determine dust transmittance based on the extracted features. Experimental results indicate that the proposed compensation method can reduce the influence of dust on infrared thermal imager's accuracy effectively.

Error analysis on measurement temperature by means dual-color thermography technique

Analysis of multi-factor on measurement improvement of an infrared imager in low-temperature environments

A wireless passive SAW sensor based on three one-port resonators and capable of simultaneous torque and temperature measurement is presented. The sensing element is made on Y+34deg cut quartz substrate and the resonant frequencies are in the range from 433 to 437 MHz. Interrogation of the sensor is performed through an RF rotary coupler by short RF pulses. A microprocessor in the interrogation unit analyses the spectrum of SAW responses and calculates a temperature compensated torque value. Experimental results show that the temperature measurement error is within plusmn1deg at any angle of the shaft and the torque measurement error does not exceed plusmn1% of full scale within the range from -40deg to +125degC

A two-stage Fabry–Perot interferometer (FPI)-based high-spectral-resolution (HSR) Rayleigh temperature lidar technology is proposed that is capable of simultaneously detecting tropospheric temperature and aerosol optical properties with high-precision. The system structure is designed and the measurement principle is analysed. A two-channel integrated FPI used forming a two-stage FPI ensures the relative stability of the two FPI spectrums. The first-stage FPI with high spectral resolution can effectively separate Mie and Rayleigh signals to derive the signal components. Two adjacent-order transmission spectrums of the second-stage FPI are just located in the two wings of Rayleigh–Brillouin (R–B) scattering spectrum to measure temperature. Two multimode polarization insensitive optical circulators used in receiver system can achieve high-efficiency utilization of signals. A narrow linewidth semiconductor laser at 852 nm is used as light source. Using the selected and optimized system parameters, the lidar performance simulation results show that in the sunny weather conditions for 0.15WSr–1 m–2 nm–1 sky brightness, with 0.3 W laser power, a 30 cm diameter telescope, 60 m range resolution and 30 min observation time, the temperature measurement errors are below 0.4 K in night-time and below 1.6 K in daytime; the relative measurement errors of backscatter ratio are below 0.04% in night-time and below 0.13% in daytime respectively up to 6 km height. Compared with the traditional FPI-based HSR technique, the technique we proposed can improve the detection accuracy of temperature by 2.5 times and can also significantly improve the detection accuracy of backscatter ratio.