Temperature Measurement Error Research Articles

Guidelines to correctly measure the lithium ion conductivity of oxide ceramic electrolytes based on a harmonized testing procedure

Ionic conductivities of Li-ion conducting ceramic electrolytes, mostly evaluated by means of impedance spectroscopy, are a key parameter decisive for their application. Nevertheless, significant deviations in the ionic conductivity of nominally identical samples are reported in literature, which are attributed to material and sample preparation as well as measurement related differences. The goal of this study is a detailed assessment of impedance measurement deviations of 10 identically prepared samples of each Li6.45La3Zr1.6Ta0.4Al0.05O12 (LLZO:Ta:Al) and Li1.3Al0.3Ti1.7(PO4)3 (LATP), respectively. By introducing a harmonized testing procedure for impedance measurement and data analysis, deviations among the participating labs were reduced to differences <1.8% for LLZO and <3.1% for LATP. A complete assessment of instrumentation (fitting, temperature and impedance measurement errors) and sample geometry related errors revealed a high measurement precision with a total error <1.1%. Further on a decreasing ionic conductivity was observed for both materials during the study. Indications for testing and storage induced aging mechanisms were obtained by additional measurements.

Bioinspired Perspiration‐Wicking Electronic Skins for Comfortable and Reliable Multimodal Health Monitoring

AbstractElectronic skins (e‐skins) have gained tremendous attention in health monitoring and disease diagnosis. However, the accumulated sweat at the skin/e‐skin interface would compromise the comfort, reliability, and fidelity for long‐term monitoring. Here, inspired by the active liquid transport phenomenon in nature, a biomimetic gold/thermoplastic polyurethane/cellulose membrane (Au/TPU/CM) based e‐skin is reported that can “pump” perspiration from the interface immediately through the combination of gradient porosity and surface energy gradient. The resulting electrode possesses good conductivity (2.68 Ω sq–1), excellent flexibility (the resistance only fluctuated 1.1% and 0.4% after 10 000 bending cycles and 2500 tensile cycles, respectively), and outstanding water vapor transmission and water evaporation rate (2.2 and 7.1 times as much as that of cotton fabric, respectively). The ultrafast perspiration‐wicking capability not only improves the wearing comfort but also minimizes the measurement error of skin hydration and temperature due to perspiration, eliminates the risk of short circuit in sensor array, and reduces the noise level, significantly enhancing the accuracy and reliability of multimodal sensing in e‐skins. The design strategy may encourage more material and structure development in e‐skins with improved sweat tolerance.

Definition of uncertainty of temperature measured via thermocouple in various sources of errors

One of the most significant issues for researchers of thermodynamic temperature measurements is the evaluation of realiability of measurement results. Thus, while thermodynamic measuring of the temperature with thermocouples, it is essential to specify uncertainty before making decision on the reliability of measuring data during temperature measurements. The research surveys justified that uncertainty of the temperature specified via thermocouple is affected by the types of errors, such as the limits of division of the structure of data collection, the error of the compensation of reference junction, the error of temperature measurement based on the specification of tension and data variability as well. During the studies different experiments using HIOKI (LR8402-20) data registrator for the definition of data changes and the errors of compensation of reference node has been carried out, as well as the procedure of specification of temperature uncertainty including compensated node uncertainty is suggested.

A multispectral thermometry based on multi-objective constraint optimization

Multispectral thermometry is a widely used non-contact temperature measurement method. How to obtain accurate target temperature under the unknown spectral emissivity is a difficult problem to be solved in this field. The emissivity assumption model method commonly used cannot be widely applied to the temperature measurement of various materials. Therefore, a multispectral thermometry based on multi-objective constraint optimization is proposed, which can accurately solve the true temperature and spectral emissivity without any prior knowledge of emissivity. In this method, the multi-objective function is established according to the radiation equations. The new emissivity constraint conditions are set for the objective function, and a mixed penalty function method is used to solve the constraint optimization problem. The simulation experiment results show that the relative error of temperature measurement for the method is less than 1%, and the average running time is less than 0.1 s, which prove the feasibility and reliability of the proposed method.

Dual-mode optical thermometry based on transparent NaY2F7:Er3+,Yb3+ glass-ceramics

NaY 2 F 7 :Er 3+ ,Yb 3+ glass-ceramics (GC) with high transmittance were well manufactured using a melt-quenching technique and subsequent thermal treatment. Structure, morphology and photoluminescence properties of all samples were thoroughly studied via X-ray diffraction, transmission and up-conversion emission spectrum. Due to the improved crystallinity after thermal treatment, the up-conversion emission intensity of GC was significantly higher than the precursor glass. The optical thermometry performances of Er 3+ ions at thermally coupled ( 2 H 11/2 / 4 S 3/2 ), and non-thermally coupled energy levels ( 2 H 11/2 / 4 F 9/2 ) were explored. Their relative sensitivities ( S R ) are 1.00% K −1 and 0.76% K −1 at 323 K, respectively. Moreover, their maximum temperature measurement errors (Δ T ) are 0.09 K and 0.12 K at 563 K, with repeatability ( R ) exceeding 99% and 98%, respectively. All of the findings suggest that NaY 2 F 7 GC are excellent self-calibration temperature measuring materials, with superior temperature resolution and repeatability.

Proton magnetic resonance spectroscopy thermometry: Impact of separately acquired full water or partially suppressed water data on quantification and measurement error

In proton magnetic resonance spectroscopy (1 H MRS) thermometry, separately acquired full water and partially suppressed water are commonly used for measuring temperature. This paper compares these two approaches. Single-voxel 1 H MRS data were collected on a 3-T GE scanner from 26 human subjects. Every subject underwent five continuous MRS sessions, each separated by a 2-min phase. Each MRS session lasted 13 min and consisted of two free induction decays (FIDs) without water suppression (with full water [FW or w]) and 64 FIDs with partial water suppression (with partially suppressed water [PW or w']). Frequency differences between the two FWs, the first two PWs, the second FW and the first PW (FW2 , PW1 ), or between averaged water ( ) and N-acetylaspartate (NAA), were measured. Intrasubject and intersubject variations of the frequency differences were used as a metric for the error in temperature measurement. The intrasubject variations of frequency differences between FW2 and PW1 , calculated from the five MRS sessions for each subject, were larger than those between the two FWs or between the first two PWs (p = 1.54 x 10-4 and p = 1.72 x 10-4 , respectively). The mean values of intrasubject variations of for all subjects were 4.7 and 4.5 times those of and , respectively. The intrasubject variations of the temperatures based on frequency differences, or ( ), were about 2.5 times greater than those based on averaged water and NAA frequencies ). The mean temperature measured from ) (n = 26) was 0.29°C lower than that measured from and was 0.83°C higher than that from ( ). It was concluded that the use of separately acquired unsuppressed or partially suppressed water signals may result in large errors in frequency and, consequently, temperature measurement.

Development of a Smart Clinical Bluetooth Thermometer Based on an Improved Low-Power Resistive Transducer Circuit.

Smart sensors have been used in many engineering monitoring and control applications. This work focuses on the development of a new type of clinical Bluetooth thermometer, based on an improved low-power resistive transducer circuit. Most existing resistive transducers use relatively complicated circuits with higher cost and power consumption. To tackle these problems, especially in real applications, an improved low-power resistive transducer circuit is proposed in this work and is used to develop smart Bluetooth thermometers. The parameters of the resistive transducer circuit are selected by quantitative analysis and optimization to improve the performance of the low-power resistive transducer circuit. The effectiveness of the proposed design technology was verified by tests. The temperature measurement error of the new smart Bluetooth thermometer is less than 0.1 °C, which can not only meet the clinical use requirements but also has lower cost and power consumption.

Diffuse back-illumination temperature imaging (DBI-TI), a novel soot thermometry technique

To meet stringent emissions regulations on soot emissions, it is critical to further advance the fundamental understanding of in-cylinder soot formation and oxidation processes. Among several optical techniques for soot quantification, diffuse back-illumination extinction imaging (DBI-EI) has recently gained traction mainly due to its ability to compensate for beam steering, which if not addressed, can cause unacceptably high measurement uncertainty. Until now, DBI-EI has only been used to measure the amount of soot along the line of sight, and in this work, we extend the capabilities of a DBI-EI setup to also measure in-cylinder soot temperature. This proof of concept of diffuse back-illumination temperature imaging (DBI-TI) as a soot thermometry technique is presented by implementing DBI-TI in a single cylinder, heavy-duty, optical diesel engine to provide 2-D line-of-sight integrated soot temperature maps. The potential of DBI-TI to be an accurate thermometry technique for use in optical engines is analyzed. The achievable accuracy is due in part to simultaneous measurement of the soot extinction, which circumvents the uncertainty in dispersion coefficients that depend on the optical properties of soot and the wavelength of light utilized. Analysis shows that DBI-TI provides temperature estimates that are closer to the mass-averaged soot temperature when compared to other thermometry techniques that are more sensitive to soot temperature closer to the detector. Furthermore, uncertainty analysis and Monte Carlo (MC) simulations provide estimates of the temperature measurement errors associated with this technique. The MC simulations reveal that for the light intensities and optical densities encountered in these experiments, the accuracy of the DBI-TI technique is comparable or even better than other established optical thermometry techniques. Thus, DBI-TI promises to be an easily implementable extension to the existing DBI-EI technique, thereby extending its ability to provide comprehensive line-of-sight integrated information on soot.

High-precision nuclear magnetic resonance probe suitable for in situ studies of high-temperature metallic melts

High-temperature nuclear magnetic resonance (NMR) has proven to be very useful for detecting the temperature-induced structural evolution and dynamics in melts. However, the sensitivity and precision of high-temperature NMR probes are limited. Here we report a sensitive and stable high-temperature NMR probe based on laser-heating, suitable for in situ studies of metallic melts, which can work stably at the temperature of up to 2000 K. In our design, a well-designed optical path and the use of a water-cooled copper radio-frequency (RF) coil significantly optimize the signal-to-noise ratio (S/NR) at high temperatures. Additionally, a precise temperature controlling system with an error of less than ± 1 K has been designed. After temperature calibration, the temperature measurement error is controlled within ± 2 K. As a performance testing, 27Al NMR spectra are measured in Zr-based metallic glass-forming liquid in situ. Results show that the S/NR reaches 45 within 90 s even when the sample’s temperature is up to 1500 K and that the isothermal signal drift is better than 0.001 ppm per hour. This high-temperature NMR probe can be used to clarify some highly debated issues about metallic liquids, such as glass transition and liquid–liquid transition.

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 low power-integrated temperature sensor interface circuit

This paper constructs and simulates the interface circuit of a temperature sensor based on SMIC 0.18 [Formula: see text]m CMOS. The simulation results show that when the power supply voltage is 1.8 V, the chopper op-amp gain is 89.44 dB, the low-frequency noise is 71.83 nV/Hz,[Formula: see text] and the temperature coefficient of the core temperature sensitive circuit is 1.7808 mV/[Formula: see text]C. The sampling rate of 10-bit SAR ADC was 10 kS/s, effective bit was 9.0119, SNR was 59.3256 dB, SFDR was 68.7091 dB, and THD was −62.5859 dB. The measurement range of temperature sensor interface circuit is −50[Formula: see text]C[Formula: see text]C, the relative temperature measurement error is ±0.47[Formula: see text]C, the resolution is 0.2[Formula: see text]C/LSB, and the overall average power consumption is 434.9 [Formula: see text]W.

Extracting Brillouin frequency shift accurately based on particle swarm optimization and a cross-correlation method.

A fitting algorithm based on particle swarm optimization (PSO) and the cross-correlation method (XCM) was proposed to accurately extract features of the Brillouin scattering spectrum. Both the simulation and experiment were conducted to verify the validity of the proposed algorithm. The results show that the algorithm achieves high demodulation accuracy and is suitable for Brillouin scattering spectra with different signal-to-noise ratios, full width at half-maximums, frequency sweep intervals, and spectral symmetries. Compared with the Lorenz curve fitting and XCM algorithm, the extraction error of the PSO-XCM can be optimized up to 99.98% and 99.93%, and the fitting degree can be improved by 98%. Moreover, based on the proposed algorithm, the minimum temperature measurement error can reach 0.06°C and the Brillouin frequency shift measurement error is 0.07 MHz in 10 km sensing fiber for the Brillouin optical time domain analysis (BOTDA) sensing system.

Assessment of radiative heating errors in Tropical Atmosphere Ocean array marine air temperature measurements

We assess the radiative heating error affecting marine air temperature (MAT) measurements in the Tropical Atmosphere Ocean array. The error in historical observations is found to be ubiquitous across the array, spatially variable and approximately stationary in time. The error induces spurious warming during daytime hours, but does not affect night-time temperatures. The range encompassing the real, unknown daily- and monthly-mean values is determined using daytime and night-time mean temperatures as upper and lower limits. The uncertainty in MAT is less than or equal to 0.5 °C and 0.2 °C for 95% of daily and monthly estimates, respectively. Uncertainties impact surface turbulent heat flux estimates, with potentially significant influences on the quantification of coupled ocean-atmosphere processes.

Development of a Monitoring System to Assess the Internal Environment of Bagged Grain in Storage

HighlightsA temperature and relative humidity monitoring system for bagged grain was developed.Continuous monitoring of condition of bagged corn and paddy was done for four months.Temperature and relative humidity within bagged grain followed the ambient conditions.Equilibrium moisture content of the stored grain increased by 1.2% during storage.Abstract.Most farmers in African countries produce small amounts of grain per season and use polypropylene bags for grain storage. Little published information is available on the temperature and moisture change of bagged grain even though high losses are observed. Commercially available moisture meters are expensive and not suitable for providing real-time information on the condition of bagged grain. A monitoring system was developed to assess the internal environment of bagged grain stored in warehouses. The system has eight on-board integrated temperature and relative humidity sensors connected to a custom Arduino-based data acquisition system which recorded a time stamp, temperature, and relative humidity onto a microSD card. Four units were deployed in two warehouses in Nigeria from 3 May 2019 to 9 September 2019. There were 54 bags of corn in Ilorin, and 4000 bags of paddy rice in Tede. Average monthly temperatures recorded at various locations in the warehouse were significantly different (p&amp;lt;0.05). The errors in temperature and relative humidity measurement were 0.2°C and 3.7%, respectively. Equilibrium moisture content of bagged corn and paddy increased by 1.1 and 1.2 percentage points (wet basis), respectively. Data acquired by the system can be used to monitor the condition of bagged grain and detect potential spoilage. This system would help warehouse managers make informed decisions to reduce storage losses. Keywords: EMC, Grain bag storage, Loss management, Moisture, Resilience, Temperature.

SOI Waveguide Bragg Grating Photonic Sensor for Human Body Temperature Measurement Based on Photonic Integrated Interrogator.

A waveguide Bragg grating (WBG) provides a flexible way for measurement, and it could even be used to measure body temperature like e-skin. We designed and compared three structures of WBG with the grating period, etching depth, and duty cycle. The two-sided WBG was fabricated. An experimental platform based on photonic integrated interrogator was set up and the experiment on the two-sided WBG was performed. Results show that the two-sided WBG can be used to measure temperature changes over the range of 35–42 °C, with a temperature measurement error of 0.1 °C. This approach has the potential to facilitate application of such a silicon-on-insulator (SOI) WBG photonic sensor to wearable technology and realize the measurement of human temperature.

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

Obtaining soil thermophysical parameters is the premise for design ground heat exchanger in ground source heat pump system, but it may not be accurately determined due to the limitations of the analytical models. In this paper, artificial neural network (ANN) is used to directly establish the mapping relationship between temperature response and soil thermophysical parameters, and the identification accuracy of traditional method and ANN under different measurement errors is compared. In addition, Kalman filter and fitting regression are used to remove the interference noise. The results show that the identification accuracy and stability of the traditional method are relatively weak affected by temperature measurement error, but the identification accuracy is limited. The maximum deviation errors of thermal conductivity and volumetric heat capacity are 10.68% and 18.42%, respectively, and no matter which kind of noise reduction method cannot improve the identification accuracy. The identification stability of ANN is relatively greatly affected by temperature measurement error, but the identification accuracy is high. The maximum deviation errors of the two parameters are 10.05% and 5.4%, respectively. Through the logarithmic function fitting of noise date can further improve the identification accuracy and stability, the maximum deviation errors are only 2.12% and 3.65%.

Анализ погрешности измерения температуры образцов высокотемпературной керамики при различных способах заделки термопар

The evaluation of methodological errors in measuring the temperature of nitride ceramics under unilateral heating by high-intensity heat flow was carried out. Simulation of thermal processes in the temperature sensor — sample system was performed using the Siemens PLMNX program. Various methods of fixing platinum-rhodium thermocouples with a diameter of 0.1 mm on the surface and inside the samples have been investigated. The regularities of the influence of the size of the hot junction, the presence of thermal cement, the shape of the grooves for fixing thermocouples on the methodological error of temperature measurement were investigated. Significant errors were revealed when installing thermocouples on the surface of the sample without violating its integrity. Recommendations for the installation of thermocouples were given. The results of the paper can be useful in the preparation of experimental samples for thermal tests on radiation heating stands.

Investigating photomultiplier tube nonlinearities in high-speed phosphor thermometry using light emitting diode simulated decay curves.

Photomultiplier tube (PMT) nonlinearities relevant for single shot high-speed lifetime phosphor thermometry were investigated by simulating decay curves with a light emitting diode (LED) at repetition rates between 1Hz and 10kHz. The PMT gain, LED decay time, and background radiant flux were also varied to investigate their impact on the measured decay time error. Errors in the measured decay time due to nonlinear PMT performance lead to temperature measurement errors; therefore, having the measured decay time sensitive to only phosphor temperature is highly valuable for more reliable temperature measurements. Photocathode bleaching had a significant impact on the signal level linearity for PMTs with excitation frequency in the kHz regime but had a smaller impact on the decay time error. Space charge effects were most noticeable at high radiant flux levels and high repetition rates. Strong background radiant flux may lead to decay time errors, and a gateable photocathode could be an effective method to reduce decay time errors. The best decay time measurement configuration to maximize precision without sacrificing accuracy is to use PMT gain in the recommended range and the highest radiant flux where the PMT response is still linear. The degree of nonlinearity in the PMT response is partly detector dependent; therefore, the results in this work may differ among detectors; however, the analysis presented in this work provides guidelines for improving the temperature accuracy of kHz lifetime phosphor thermometry measurements.

Reflectogram shape deformation in distributed fibre systems in the presence of spontaneous noise in the probe radiation

We report a study of the effect of spontaneous emission-induced noise in probe pulsed radiation on the reflectogram shape deformation in a distributed temperature sensor based on Raman scattering of light. Since the fraction of spontaneous emission in the used erbiumdoped amplifier can reach 50 % of the total power, this leads to deviations of reflectograms in the temperature sensor from the theoretical exponential dependence and, as a result, can yield a temperature measurement error of several degrees. Filtering the radiation with an amplitude modulator makes it possible to reduce these deviations. The influence of spontaneous emission on reflectograms is studied theoretically and experimentally.

YOLOv4 를 활용한 열화상 기반 얼굴영역 체온 측정 인공지능 시스템

Due to the recent spread and long-term continuation of COVID-19, numerous non-contact body temperature measuring equipment is being introduced in public places to prevent cross-infection. Therefore, extensive research on the non-contact body temperature measurement method, using a thermal imaging camera, is being conducted globally. The existing method of measuring the body temperature using a thermal imaging camera has several limitations including a severe temperature deviation while measuring the body temperature, blurring of the location of the set measuring point, or not obtaining an accurate measurement due to obstacles. To overcome these limitations, we used deep learning to detect faces in thermal images, and measure the body temperature using a multipoint-based image processing with histograms of the detected areas. The proposed deep-learning-based method exhibited several advantages such as higher accuracy, wide area coverage, and efficient detection irrespective of obstacles. Compared to the conventional body temperature measurement, that proposed in this paper resulted in an average body temperature measurement error rate of less than 2%.