High-precision Temperature Measurement Research Articles

Implementation of Linear Regression Method for Calibration and Temperature Measurement on PT100 Temperature Sensor

The PT100 temperature sensor, a type RTD (resistance temperature detector), is widely employed in industries, particularly for steam boiler temperature regulation. Precise temperature measurement is vital for operational efficiency and safety maintenance. Utilizing linear regression for calibrating and measuring temperature with the PT100 sensor integrated with Arduino Uno and LCD I2C is proposed to enhance accuracy. Testing involved assembling the PT100 sensor with Arduino Uno and LCD I2C. Test data were employed for linear regression to derive the calibration equation. Measurements were conducted by comparing PT100 sensor readings with a digital thermometer across a temperature range of 30ºC to 75ºC at 5ºC intervals, with each temperature point tested five times. Results exhibit good accuracy in temperature measurement with the PT100 sensor, featuring low error and percentage error. The standard deviation indicates consistent measurement. Integration of the PT100 temperature sensor with Arduino Uno and LCD I2C, coupled with linear regression for calibration, yields a precise temperature measurement system. Testing against a digital thermometer demonstrates highly accurate outcomes. This developed system finds application in high-precision temperature measurement for steam boiler operations.

A temperature sensor based on multi-beam capture and interference

In this study, we proposed and validated a temperature fiber sensor based on optical signal capture Mach-Zehnder Interferometer (OSC-MZI) with high-precision temperature measurement capabilities. By creating three air cavities on a continuously offset-spliced no-core fiber (NCF), the optical signal experiences reflection and divergence within these cavities, which enhances the optical path of propagating light. Gradually, filling these NCF cavities with polymethyl methacrylate (PMMA) microspheres to increase the light coupling efficiency and as a sensing unit. Due to the directly contact between the optical fiber waveguide and PMMA, the state of incident lights is easily influenced by the refractive index (RI) variations of PMMA. When the environmental temperature changes, RI of the PMMA with high thermal-optic coefficient shows marked change, which finally leads to the obvious wavelength shift of interference dips in the transmission spectrum. Experimental results show that MZI coated with the polymer materials achieves a temperature sensitivity of up to 2.04 nm/°C within the temperature range of 25–50 °C. Furthermore, as an interference-based MZI sensor, its total length is only 4.75 mm. The proposed OSC-MZI provides a new approach for combining optical fiber sensors with polymer materials.

High-sensitivity ratiometric thermometers of Yb3+/Er3+/Tm3+ co-doped LuScO3 single crystal fibers based on non-thermally coupled energy levels

Fluorescence thermometry manifests tremendous attention for their potential applications in the temperature sensing, especially for combining wide operating temperature range with high sensitivity. However, the use of thermally coupled energy levels (TCLs) for temperature measurement has strict requirements for energy difference, which limits the sensitivity of detection. In order to satisfy higher sensitivity sensing, the pair of non-thermally coupled energy levels (NTCLs) of 4S3/2 and 3H4 has been innovatively designed. Herein, the sesquioxide Yb,Er,Tm co-doped LuScO3 single crystal fibers (SCFs) had been delicately grown by Laser Heated Pedestal Growth (LHPG) method. The fluorescence intensity ratio (FIR) thermometry was realized based on the Er3+:4S3/2→4I15/2 (545–593 nm) and Tm3+:3H4→3H6 (750–850 nm) NTCLs. Such an obvious FIR-temperature change through the NTCLs presents an outstanding optical thermometric performance, yielding the high temperature sensing with wide range. The maximum value of absolute sensitivity was 2 orders of magnitude higher than the temperature measurement using TCLs. More importantly, the sesquioxide Yb,Er,Tm:LuScO3 SCFs exhibit superior thermal stability that will be helpful to obtain high precision temperature measurement. Hence, our findings might offer some useful inspiration for exploring high-sensitivity luminescent thermometers and enriching the research of temperature measuring materials.

High-precision and wide-range temperature measurement and control system of satellite-borne calibration blackbody

The accurate measurement and control of blackbody temperature can play an important role in radiometric calibration. A novel circuit suitable for the aerospace environment is designed to measure and control the temperature of the blackbody. A coarse-fine measurement method considering the wire resistance and self-heating effect of the platinum resistance is presented to calculate the resistance values of the platinum resistors. The precision of temperature measurement is improved using a line fitting algorithm with error calibration and temperature drift error compensation. A fuzzy self-adaptive PID controller is designed to improve the temperature control effect. The performances of the developed system are implemented on an FPGA/A3PE3000-FG484I controller board. The test results show that the device temperature measurement precision can reach ±0.03K for the entire temperature range 238 K to 367 K, the temperature stability is better than 0.02 K/20 s, and the temperature uniformity is better than 0.1 K.

High precision temperature measurement for cryogenic temperature sensors based on deep learning technology

Nonlinear error compensation is a significant factor that affects the measurement accuracy of temperature sensors. Cryogenic temperature sensors require a precise calibration technique to achieve accurate temperature measurements. BP (Back Propagation) neural networks are not suitable for sensor temperature prediction due to slow convergence and poor learning ability. In this study, a Chebyshev polynomial-based BiLSTM (Bi-directional Long Short-Term Memory) algorithm (C-BiLSTM) is proposed to improve the accuracy of measurement. Firstly, we demonstrate vacuum packaged temperature sensors based on zirconium oxynitride (ZrOxNy) thin films with ultra-high sensitivity at cryogenic temperatures. Secondly, a dataset consisting of sensor resistance and temperature values was obtained from five above-mentioned sensors, which contains 29 calibration points in the temperature range of 16 K-300 K measured by the Calibration System. Then, the dataset was divided into two temperature ranges (16 K-54.358 K and 40 K-300 K). In the range 16–54.358 K, 14 set-points are selected as training set and 3 set-points as testing set. In the range 40–300 K, 12 set-points are selected as training set and 2 set-points as testing set. Thirdly, a neural network model was built and trained using the TensorFlow framework. By comparing C-BiLSTM we proposed with the BP neural network and BiLSTM, the results show that the C-BiLSTM model converges faster and greatly improves the prediction accuracy after adding Chebyshev polynomial features. The fitting error and prediction error are less than 1 mK in the temperature range of 16 K-40 K. They can also keep less than 10 mK even at the wide temperature range of 40 K-300 K, which is a significant improvement respect to improving the accuracy of temperature measurement.

High-Precision Temperature Measurement Using Frequency-Division Multiplexing Laser Dispersion Spectroscopy for Dynamic Combustion Monitoring

High-Precision Temperature Measurement Using Frequency-Division Multiplexing Laser Dispersion Spectroscopy for Dynamic Combustion Monitoring

Mid-infrared dual-comb spectroscopy for rapid temperature distribution characterization.

Due to the influence of chemical reactions, phase change, and other phenomena, the combustion system is a complicated high-temperature environment. Therefore, the spatio-temporally resolved monitoring of the temperature field is crucial for gaining a comprehensive understanding of the intricate combustion environment. In this study, we proposed a fast and high-precision temperature measurement technique based on mid-infrared (MIR) dual-comb spectroscopy with a high spectral resolution and fast refresh rate. Based on this technique, the spatio-temporally resolved measurement of a non-uniform temperature field was achieved along the laser path. To verify the capability of DCS for temperature measurement, the bandhead ro-vibrational lines of the CO2 molecule were acquired, and the 1-σ uncertainty of the retrieved temperature was 3.2°C at 800°C within 100 ms. The results demonstrate the potential of our fast and high-precision laser diagnostic technique which can be further applied to combustion kinetics.

The Hydrostatic Mass of A478: Discrepant Results from Chandra, NuSTAR, and XMM-Newton

Galaxy clusters are the most recently formed and most massive, gravitationally bound structures in the Universe. The number of galaxy clusters formed is highly dependent on cosmological parameters, such as the dark matter density, σ 8, and Ω m . The number density is a function of the cluster mass, which can be estimated from the density and temperature profiles of the intracluster medium under the assumption of hydrostatic equilibrium. The temperature of the plasma, hence its mass, is calculated from the X-ray spectra. However, effective-area calibration uncertainties in the soft band result in significantly different temperature measurements from various space-based X-ray telescopes. NuSTAR is potentially less susceptible to these issues than Chandra and XMM-Newton, having larger effective area, particularly at higher energies, enabling high-precision temperature measurements. In this work, we present analyses of Chandra, NuSTAR, and XMM-Newton data of A478 to investigate the nature of this calibration discrepancy. We find that NuSTAR temperatures are on average ∼11% lower than those of Chandra, and XMM-Newton temperatures are on average ∼5% lower than those of NuSTAR. This results in a NuSTAR mass at r 2500,Chandra of M ⊙, which is ∼10% lower than that of M 2500,Chandra and ∼4% higher than M 2500,XMM−Newton.

Achieving high-precision dual-mode temperature measurement in the photothermal conversion process of SrIn2O4: Er3+, Yb3+ phosphors

Accurate measurement of temperature during photothermal conversion is crucial for the application of up-conversion photothermal conversion fluorescent materials. In this paper, a kind of SrIn2O4: Yb3+, Er3+ up-conversion phosphor with strong photothermal conversion ability and high-precision dual-mode temperature measurement performance was synthesized by high-temperature solid-state method. Under 980 nm laser excitation, a high-precision temperature measurement with a maximum relative sensitivity of Sr = 1.2 %K−1 was achieved by using the fluorescence intensity ratio of the thermally coupled energy level pairs (2H11/2/4S3/2) of Er3+ ions. In addition, we found that the luminescent color of the synthesized phosphor can span a large color gamut interval with the rise of temperature, realizing the optical temperature measurement based on temperature-induced color coordinate shift. On this basis, we realized dual-mode temperature monitoring and temperature self-calibration during the photothermal conversion process of SrIn2O4: Yb3+, Er3+ phosphors. These results are of great practical value for the application of photothermal conversion fluorescent materials in micro-zone heating and temperature self-monitoring.

Fluorescent sensing probe based on heterovalent doped Lu2W2.5Mo0.5O12:Er3+/Yb3+ phosphor for real-time chip temperature monitoring

The influence of Li+/Zn2+ heterovalent doping on the structural change and upconversion luminescence properties of Lu2W2.5Mo0.5O12:Er3+/Yb3+ phosphors was investigated in details. The gradual substitution of Li+/Zn2+ ions for Lu3+ ions result in the evolution from orthorhombic Lu2W2.5Mo0.5O12 to monoclinic (LiZn)2W2.5Mo0.5O12, which bring the structural distortion, the reduction of local symmetry and the crystallite growth. The green upconversion intensity of Er3+ ions at 536 nm and 550 nm were enhanced significantly by a factor of 8000 and 4000. The temperature sensing characteristics of a single (LiZn)2W2.5Mo0.5O12:Er3+/Yb3+ particle in all-fiber structure was explored and the unusual thermally-enhanced upconversion luminescence was observed, which is beneficial for achieving high-precision temperature measurement based on the fluorescence intensity ratio technology. The absolute temperature sensitivity reached a maximum of 0.0095 K−1 at 423 K and the temperature deviation was less than 0.6 K. The as-built all-fiber temperature sensor was successfully applied in the on-line monitoring of CPU temperature.

Ultrasensitive temperature sensor based on optic fiber Fabry–Pérot interferometer with Vernier effect

An ultrahigh sensitivity optic fiber temperature sensor with cascaded two Fabry–Pérot​ interferometers (FPIs) based on the Vernier effect has been fabricated and experimentally demonstrated. One polymer-cavity FPI is used as a sensing FPI and another fiber-cavity is used as a reference FPI to generate the Vernier effect. The experimental results show that the fabricated FPIs sensor has the high temperature sensitivity of −83.130 nm/°C and a high linear response (R-square: 0.9976), which is almost ∼39 times higher than that of an individual polymer-cavity FPI sensor (∼2.080 nm/°C). The stability experiment is also carried out, and the maximal variation of the wavelength shift of the interference fringes is 2.005 nm for a long-term testing. With its advantages of easy fabrication, low cost and small volume, the proposed sensor has significant benefits in terms of various practical applications that need high precision temperature measurement.

The Effect of Pseudofrazil Particle Entrainment on Salinity Measurements

AbstractSalinity effects of particles entrained into conductivity cells have previously mainly been studied in the context of suspended sediment. Particles influencing conductivity cells can also be small ice crystals (frazil) that may form in supercooled water. The detection of supercooled water depends on accurate, high precision temperature, salinity and pressure measurements. As it is currently not possible to measure salinity in situ, the standard procedure is to measure conductance over a known volume and calculate salinity. Frazil ice entrained into a conductivity cell changes the volume of conductive fluid in the conductivity cell, thus changing the conductivity, salinity and supercooling measurements. We present results on the effect of entraining microplastic into a Sea‐Bird Electronics conductivity cell to simulate the effect of frazil. We show that particle volumes comparable to frazil volumes observed in the ocean change the measured conductivity and led to changes in calculated supercooling between 0.3 and 10 mK, possibly up to the same order of magnitude as naturally observed supercooling in the ocean. Further, we demonstrate that where supercooling is present, natural frazil ice concentrations can have an appreciable effect on parameters calculated with both the Equation of State of Seawater 1980 and Thermodynamic Equation of Seawater 2010 equations of state of seawater. Thus, to ensure accurate measurements in locations of very high frazil concentration, the entrainment of frazil needs to be prevented, which is not possible with methods currently available, or corrected for. An example for such a correction is given and could be modified to be applicable to other particles, for example, sediment.

A High-Precision Temperature Measurement Method Through Correcting Reflected Radiation Under High-Temperature Background

In this paper, a high precision correction method for temperature measurement errors due to reflected radiation under high temperature background is reported by applying calibration experiments. The correction theory governing the temperature measurement errors caused by reflected radiation is derived in principle, and the physical field model of temperature measurement is established for a ceramic blade in a high temperature furnace. The temperature measurement errors before and after the correction of the reflected radiation are analyzed through simulations, and the reflected radiation in the temperature measurement environment of the blade is calibrated. The experimental results show that the errors of monochromatic and colorimetric temperature measurements are decreased from 13.5% and 7.5% to 0.3% and 0.5%, respectively. The results indicate that the proposed method can significantly decrease the temperature measurement errors caused by reflected radiation.

Resistive-Based Micro-Kelvin Temperature Resolution for Ultra-Stable Space Experiments.

High precision temperature measurements are a transversal need in a wide area of physical experiments. Space-borne gravitational wave detectors are a particularly challenging case, requiring both high precision and high stability in temperature measurement. In this contribution, we present a design able to reach 1 μK/Hz in most of the measuring band down to 1 mHz, and reaching 20 μK/Hz at 0.1 mHz. The scheme is based on resistive sensors in a Wheatstone bridge configuration which is AC modulated to minimize the 1/f noise. As a part of our study, we include the design of a test bench able to guarantee the high stability environment required for measurements. We show experimental results characterising both the test bench and the read-out, and discuss potential noise sources that may limit our measurement.

Study and Design of a Multi-range Programmable Sensor for Temperature Measurement

In this paper, a wide-range high-precision sensor has been designed in order to accurately measure the temperature in a medium with arbitrary temperature variation and the implementation of a wide-spectrum temperature measurement system with a self-selected multi-sensor has been realized. This multi-sensor core is made up of different sensors combined to measure different temperature ranges. This concept can be used for high-precision temperature measurement in electrical capacitance tomography applications. The proposed technique is well suited for temperatures in boilers, industries, and everywhere high temperature measurement sensitivity is needed by using different combined temperature sensors of high precision.

Health checkup test of the standard cosmological model in view of recent cosmic microwave background anisotropies experiments

We present an updated data-analysis comparison of the most recent observations of the Cosmic Microwave Background temperature anisotropies and polarization angular power spectra released by four different experiments: the Planck satellite on one side, and the Atacama Cosmology Telescope (ACTPol) and the South Pole Telescope (SPT-3G), combined with the WMAP satellite 9-years observation data in order to be "Planck-independent" on the other side. We investigate in a systematic way 8 extended cosmological models that differ from the baseline $\Lambda$CDM case by the inclusion of many different combinations of additional degrees of freedom, with the aim of finding a viable minimal extended model that can bring all the CMB experiments in agreement. Our analysis provides several hints for anomalies in the CMB angular power spectra in tension with the standard cosmological model that persist even in these multi-parameter spaces. This indicates that either significant unaccounted-for systematics in the CMB data are producing biased results or that $\Lambda$CDM is an incorrect/incomplete description of Nature. We conclude that only future independent high-precision CMB temperature and polarization measurements could provide a definitive answer.

Design of a high-precision, high environmental adaptability temperature measurement system for environments with large temperature variations

A high-precision, high environmental adaptability thermometer based on proportional divider resistance is proposed for high-precision temperature measurement in a spaceborne environment subjected to large temperature variations. In this method, a constant voltage source was used instead of the traditional current source to increase the short-term stability of the proportional divider resistance measurement. The temperature drift characteristics of the measurement system were analyzed and compensated by the self-calibration of the reference resistance method. Based on the above-mentioned method, the minimum noise requirements were analyzed and designed for each unit of the thermometer. The temperature measurement performance of the thermometer was tested by an equivalent temperature measurement experiment with a precision resistance box and a temperature comparison experiment with platinum resistance (PT1000). The equivalent experimental results showed that the resolution of the thermometer was 0.3 mK at an ambient temperature of 20 °C and the maximum deviation of the measurement error was less than 1 mK in a large working range of 10–40 °C. The comparison experiment using a Fluke thermometer 1594A as the reference instrument showed that the standard deviation of temperature measurement was within 0.8 mK in the range of 17–23 °C.

Experimental study of a tapered fiber temperature sensor with a liquid seal based on multimode interference

Studying high-sensitivity fiber-optic temperature sensors is vital in pursuing high-precision temperature measurement. We propose a liquid-sealed multimode interference fiber temperature sensor with a double-taper structure. The influence of structure and sealed-liquid material on the temperature sensitivity of the sensor is analyzed experimentally. The results show that the tapered structure can effectively improve the temperature sensitivity of the sensor, and the effect becomes more evident with the increased refractive index of the sealed liquid. As the refractive index of the sealed liquid increases, the temperature sensitivity of the sensor can be effectively improved. However, the sealed liquid with a high refractive index will increase the failure temperature of the sensor. Near the failure temperature, the sensor achieves an ultra-high-temperature sensitivity of -8.28nm/K. The results also prove that further increasing the refractive index of the sealed liquid no longer has a significant gain in temperature sensitivity. It is expected that the relevant research will contribute to the development of high-precision temperature-sensing systems.

Fast Simultaneous CO2 Gas Temperature and Concentration Measurements by Quantum Cascade Laser Absorption Spectroscopy

A quantum cascade laser-based sensing technique is presented which allows for in situ high-precision temperature and/or CO2 concentration measurements of gases in the room temperature regime with sampling rates up to about 40 kHz. The method is based on Boltzmann-like thermally populated fundamental and hot-band rovibrational transitions of CO2 with opposite temperature dependence. Single absorption spectra at about 2350 to 2352 cm−1 are recorded by a nanosecond frequency down chirped IR pulse of a pulsed distributed feedback quantum cascade laser (intrapulse mode). The statistical uncertainty (1σ) in the temperature measurement within one laser pulse is about 1 K and can be further reduced down to about 0.1 K by time averaging over 100 ms. Online temperature and CO2 concentration measurements on a breath simulator controlled gas flow were performed to demonstrate response-time and sensitivity for an application-driven test system.

Nonlinear dynamic thermometry: Temperature measurement using immobilized magnetic nanoparticles

We present a new method for measuring the temperature of magnetic nanoparticles that can also be adapted to immobilized particles. The Néel relaxation mechanism, which dominates the dynamic magnetization process of immobilized magnetic nanoparticles, can be used as an intermediate parameter in a sensing model to obtain temperature information. In this paper, we use the nonlinear response properties of magnetic nanoparticles to derive an analytical expression for the relationship between the phase of cubic susceptibility and temperature. We also consider dipole–dipole interactions and the dependence on field amplitude. Under experimental conditions at selected frequencies and field amplitudes, we compare temperature measurements of magnetic nanoparticles obtained with the proposed thermometry model with those obtained from existing nonlinear dielectric relaxation models. The results show that the temperature measurements obtained from the proposed model are closer to the reference temperatures in the temperature range of 308–353 K, with a standard deviation of less than 0.1 K in the temperature measurement. This new method successfully applies the nonlinear properties of magnetic nanoparticles to high-precision dynamic temperature measurements. It extends the applicability range of temperature measurement methods to conditions with strong interactions or large ac field amplitudes. This new method is expected to be applicable in anti-magnetic environments, for example, in biochemical temperature measurements of magnetically labeled cells in vivo.