Temperature Measurement System Research Articles

Quantifying laser irradiation-induced temperature field of particle reinforced metal matrix composites

While particle-reinforced metal matrix composites (PMMCs) are composed of particles and matrix with distinctly different thermomechanical properties, the thermal differences and coupled interactions between individual phases greatly determine the thermal characteristics of PMMCs under laser irradiation. In this work, we quantify the temperature evolution characteristics within SiCp/Al under laser irradiation by microstructural thermal finite element simulations and experimental investigation. Specifically, a 2D thermophysical FE model of laser-SiCp/Al interaction for the two-phase PMMCs material under laser irradiation is developed, which incorporates the temperature-dependent thermophysical properties of particles, matrix and interfaces, along with the considerations of the shape and distribution characteristics of particles, as well as the comprehensive thermal conditions. Furthermore, a 3D equivalent thermal FE model for experimental validation of predicted laser-induced temperature of SiCp/Al is developed, based on the derived equivalent properties. Meanwhile, an in-situ temperature measurement system is constructed for exploring temperature evolution characteristics during the on-going laser irradiation process, which validates a derivation of 1.7 % of predicted temperature by the equivalent thermal FE model. Finally, the impact of laser processing parameters on the temperature field of SiCp/Al is addressed. These findings provide valuable insights for understanding the thermal mechanisms of PMMCs under laser irradiation, and also the parameter optimization for laser processing of PMMCs.

Physics-data fusion for digital metering of gas-liquid two-phase flow in oil nozzles

Oil well production metering is an important basis for assessing resource reserves and production capacity. Existing metering methods require high investment and involve significant implementation difficulties and high computational costs. A new method of multiphase flow metering method was proposed by combining the fluctuation of pressure drop and temperature difference generated after throttling through the oil nozzle. The throttling equation coupling differential pressure, flow rate and gas fraction was derived. By regulating the gas and liquid superficial velocity, we carried out the experimental test for true nozzle aperture of 10 mm in the loop system, covering various flow patterns. In addition, the deep neural network was constructed for inversion prediction of mass gas fraction. The proposed flow metering equation has an adaptable gas mass fraction range of 0 to 100%, unaffected by the variations in flow patterns, gas-liquid velocities, and system pressure changes. The metering errors of gas mass fraction and mass flow rate is below ±10%. The proposed metering method only relies on the existing temperature and pressure measurement system in the gathering and transportation system, and no additional measuring devices are required. It can be widely used in oil filed production to realize the virtual metering.

Potential multi-parametric OFDR system based on the wavelength-division cross-correlation method

In this study, an optical frequency domain reflectometer (OFDR) system for simultaneous measurement of temperature, strain, and relative humidity (RH) based on the wavelength-division cross-correlation method is proposed and experimentally demonstrated. The Rayleigh scattered spectrum shifts introduced by environmental changes can be demodulated by the cross-correlation operation, and the magnitude of the shifts exhibits variability in distinct wavelength subregions. Leveraging the distinct sensitivity characteristics of different parameters across different wavelength subregions, simultaneous multi-parameter decoupling can be achieved. In the signal processing flow, the frequency domain signals in different wavelength subregions are intercepted, and then the cross-correlation operation is performed separately to obtain the spectrum shift information in different wavelength subregions. The decoupling matrix is constructed to realize the decoupling of the three parameters based on the sensitivity differences of temperature, strain, and RH in different wavelength subregions. This novel and simple multi-parameter sensing system, to the best of our knowledge, has potential applications in engineering monitoring, chemical applications, and environmental measurements.

Design of temperature measurement system guided by thermal dissipation coefficient of NTC thermistor

NTC thermistors are widely used in temperature measurement instruments due to their excellent characteristics, including high accuracy, high sensitivity, and low cost. However, the self-heating generated during their operation affects the accuracy of temperature measurements. To solve this issue, the thermal dissipation coefficients of NTC thermistors are measured in various temperature environments. For the temperature range of −40°C to 120°C, the thermal dissipation coefficient varies from 2.35 mW/°C to 2.8 mW/°C. Considering the actual circuit design, the thermal dissipation coefficient measured at a temperature increase of 15 °C is used for subsequent calculations. The maximum operating power and current that do not affect the accuracy of temperature measurement are calculated based on the coefficient. Using this as a guide, the values of the voltage divider and reference voltage are determined. The actual operating current is only half of the maximum theoretical current. The temperature measurement system, based on NTC thermistors, is designed with the constant voltage source voltage divider circuit. The temperature measurement error of the system is less than 0.08 °C. It is confirmed that NTC thermistors perform well as temperature probes under suitable circuit design.

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.

Comparison of continuous temperature measurement methods in the intensive care unit: standard bladder catheter measurements versus non-invasive transcutaneous sensors.

The purpose of this study was to compare a wearable system for body core temperature measurement versus bladder and tympanic thermometers in an intensive care setting. The question was, if continuous non-invasive sensors in the intensive care unit represent an alternative to current standard methods of invasive continuous bladder temperature measurement methods?Between May and September 2023, a comparative investigation involving 112 patients was conducted in a 20-bed surgical intensive care unit to assess various temperature probes, including those placed in the tympanic tube, bladder, and skin. To achieve this, a wireless non-invasive sensor system provided by greenTEG AG, Switzerland, was affixed to different body locations (clavicular and lateral chest) of each catheterized patient (equipped with a temperature probe) admitted to the intensive care unit. Furthermore, tympanic temperatures were recorded at specified intervals. The measurement duration ranged from a minimum of six hours to a maximum of six days, resulting in the analysis of a total of 355 simultaneous temperature measurements.In this study, a wearable temperature measurement system attached to two different body sites revealed a consistent negative bias compared to bladder temperature. In addition, the measurements were particularly influenced by body constitution. The tested system in all patients showed a mean absolute error (MAE) of 0.45°C for the lateral chest and 0.50°C for the clavicular position. Tympanic measurements had a mean absolute error of 0.35°C. In patients with body mass index (BMI) ≥ 25 the MAE increased to 0.5°C for the lateral chest and 0.56°C for the clavicular position. In contrast, the tympanic measurement had a reduced MAE of 0.32°C, which is well below this threshold when compared to bladder measurements.In conclusion the investigated system did not meet the clinically relevant acceptance criteria and showed low precision in correctly identifying fever episodes compared to invasive temperature probes, however its main advantage lies in its continuity and non-invasiveness. This makes it a potential alternative to intermittent tympanic measurement devices. In this study we were able to show, that in at least one subset of patients, the non-invasive and continuous device demonstrated a precision comparable to tympanic measurements.The accuracy of all non-invasive methods was lower than in previous studies, suggesting that the use of bladder temperature as reference and user related variations may have introduced additional errors.

Soft x-ray diagnostics system for electron temperature measurement in the integrated commissioning phase of JT-60SA.

A soft x-ray (SX) diagnostic system has been designed and installed in JT-60SA for the first plasma. For quantitative measurement, the etendue of each viewing chord was evaluated analytically and numerically. The electron temperature is evaluated from the detected bremsstrahlung emission ratio between two detector arrays with two different thicknesses of Be filters. The two filter thicknesses were optimized to be 7 and 50μm for the expected electron temperature range of 0-3keV. The one-dimensional profile of SX emission is reconstructed from line integrated emission by the elliptic Abel inversion scheme. For a plasma discharge with a plasma current of 1 MA, a peaked electron temperature profile with about 800eV at the center is obtained. The total bremsstrahlung power was also evaluated using the electron temperature profile and the absolutely evaluated etendue of each viewing chord. In this evaluation, the bremsstrahlung power is around 10% of ohmic heating power.

Time Delay Estimation for Acoustic Temperature Measurement of Loose Coal Based on Quadratic Correlation PHAT-β Algorithm

The acoustic temperature measurement method has a broad application prospect due to its advantages of high precision, non-contact, etc. It is expected to become a new method for hidden fire source detection in mines. The acoustic time of flight (TOF) can directly affect the accuracy of acoustic temperature measurement. We proposed a quadratic correlation-based phase transform weighting (PHAT-β) algorithm for estimating the time delay of the acoustic temperature measurement of a loose coal. Validation was performed using an independently built experimental system for acoustic temperature measurement of loose coals under multi-factor coupling. The results show that the PHAT-β algorithm estimated acoustic TOF values closest to the reference line as the sound travelling distance increased. The results of coal temperature inversion experiments show that the absolute error of the PHAT-β algorithm never exceeds 1 °C, with a maximum value of 0.862 °C. Using the ROTH weighted error maximum, when the particle of the coal samples is 3.0–5.0 cm, the absolute error maximum is 4.896 °C, which is a difference of 3.693 °C from the error minimum of 1.203 °C in this particle size interval. The accuracy of six algorithms was ranked as PHAT-β > GCC > PHAT > SCOT > HB > ROTH, further validating the accuracy and reliability of the PHAT-β algorithm.

Characterization of hygrothermal, gas pressure and stress characteristics for poplar wood during unilateral surface densification

Unilateral surface compression in wood presents notable benefits, including reduced wood volume loss and energy consumption, rendering a highly promising and extensive utilization. However, shortcomings in compressed wood arise due to unclear gas pressure, temperature, and moisture content distribution within the wood during hot pressing. In this paper, the temperature and pressure distribution were analyzed utilizing an optical fiber temperature and pressure measurement system within the wood during hot pressing. Moreover, the moisture content, stress and strain in each layer at the end of hot pressing were discussed extensively. The results showed that the wood surface layer (SL) and subsurface layer (SSL) maximum temperature values were similar even with different layer thicknesses. Under sealing conditions, SL and SSL temperatures were generally 6 ℃ to 7 ℃ higher compared to unsealing conditions. The gas pressure maximum value exhibited an opposite order, gradually transferring to the core layer (CL) and declining as the processing time extended. During compression treatment, moisture migrated from the hot end to the cold within the wood. The moisture content displayed significant differences between the middle and end parts of the wood under unsealed conditions, with the disparity becoming more pronounced further away from the hot end. The transition region of the compressed wood served as a stress concentration area, experiencing the highest levels of stress. The dense region followed with the second highest stress levels, while the un-densified region exhibited the least amount of stress. Under the same process parameters, the thickness had little influence on the distribution of dense layers.

A Real-Time In Situ Wafer Temperature Measurement System Based on Fiber Bragg Grating Array

A Real-Time In Situ Wafer Temperature Measurement System Based on Fiber Bragg Grating Array

Temperature prediction based on long short‐term memory convolutional neural network Bragg grating sensing

AbstractTo address the constraints associated with conventional fitting techniques for temperature demodulation in the context of subway tunnel fires, a new method of demodulation grating sensing spectrum using long short‐term memory convolutional neural network (LSTM‐CNN) is proposed in this paper. Build the monitoring platform based on LSTM‐CNN ultra‐weak fiber grating temperature measurement system, predict its sensing signals by LSTM‐CNN algorithm, select 18000 spectra as sample data for training, use AdamW stochastic optimization algorithm for training, and carry out the temperature calibration and demodulation error analysis of the Fiber Bragg Grating within the temperature range of 25–75°C. Compared with GRU algorithm, LSTM algorithm and traditional maximum peak method, the algorithm of this paper is good and can effectively improve the measurement accuracy, the experimental results show that: the demodulation accuracy of temperature wavelength prediction in this paper can be up to 99.27%, and the root mean square deviation is 0.08528°C, through the experiments, it is verified that the method proposed in this paper has a certain reference and support in terms of theories and technology significance. It is suitable for the identification and monitoring of fire hazards in underground tunnels, and also has application value in the signal processing of grating array sensing demodulation system.

Research on a dedicated thin-film thermocouple testing system for transient temperature measurement

The thin-film thermocouple (TFTC) is featured on small heat capacity and rapid response speed for transient temperature measurements under narrow space and difficult installation. Consequently, we propose a novel transient temperature testing system specifically designed for TFTC. This system features signal conditioning circuits with extended bandwidth and superior transfer speeds, a cold junction compensation method that supports customizable indexing tables, and an adaptive data filtering approach that precisely balances the smoothing of steady-state data with rapid responsiveness to transient data. This approach effectively mitigating the measurement distortion of transient temperature signals and the nonlinear phenomenon in cold junction compensation for TFTC. Utilizing NiCr/NiSi TFTC, we evaluated the system’s accuracy, demonstrating a precision range of −0.5 °C–0.25 °C within 20 °C–100 °C, and a response delay under 0.1 ms. Compared to traditional thermocouple measurement systems, our system exhibits a finer time-domain resolution. Lastly, we successfully applied this system to observe the response of TFTC under the thermal load of short-pulse laser shocks, measuring a time constant of only 1.16 ms for the TFTC. This novel transient temperature testing system provides a new approach for TFTC to achieve online dynamic measurement and online calibration, and provides technical support for TFTC measurement technology towards engineering applications.

Fiber Bragg grating sensing system for temperature measurements based on optically injected DFB-LD with an OEO loop

A novel fiber Bragg grating (FBG) sensing system, based on an optically injected distributed feedback laser diode (DFB-LD) with an optoelectronic oscillating (OEO) loop, is proposed and experimentally demonstrated for temperature measurements with high and tunable sensitivity. The FBG sensor device works as an edge filter to adjust the optical power of the injected beam in response to temperature variations. The optically injected DFB-LD works at Period-one (P1) oscillating state, and the central wavelength of the oscillating mode of the DFB-LD can be tuned by the variable power of the injected beam. Furthermore, an OEO loop is implemented to improve the signal quality of the generated P1 microwave signal. Hence, the sensing parameter of temperature is converted to the frequency variation of the generated P1 microwave signal in the proposed sensing system. In the proof-of-concept experiment, a series of P1 microwave signals are generated while different temperatures are applied to the FBG sensor. The sensitivity of the proposed FBG sensing system for temperature measurements can be tuned from 0.44322 GHz/°C to 1.25952 GHz/°C. The stability and repeatability experiments are also performed, demonstrating the high measurement accuracy (0.0629°C) and low error of the system. The proposed FBG-based sensing and interrogation system exhibits high sensitivity, large tunability, good linearity, and flexible sensing generality.

Damage characteristic of electronic devices caused by products generated by Al/Ep/KMnO4/TiH2 active material projectile hypervelocity impacting on aluminum target

As the space environment becomes more competitive, space offense and defense are increasing every day. Projectiles made of reactive materials can achieve highly effective target destruction due to their good penetration, ignition and detonation capabilities as the kill element in space attacks. When a spacecraft encounters a hypervelocity impact from a projectile of active material, it will have a serious impact on the surface material and internal electronics (logic chips, super-capacitors, etc.), leading to anomalies in the spacecraft's on-orbit operation. In order to study the damage characteristics of internal typical logic chips and super-capacitor modules caused by the hypervelocity impact of active material projectiles on the surface of spacecraft, the simulated satellite experiment of Al/Ep/KMnO4/TiH2 active material projectiles hypervelocity impacting on aluminum target was performed. By using the self-built experimental loading system, plasma characteristic parameter diagnosis system, radiation temperature measurement system and electronic device function detection system, the characteristic parameters of plasma, light flash radiation temperature, temperature evolution process of logic chip and super-capacitor at specific position under different impact velocities are obtained. When the damage behavior of Al/Ep/KMnO4/TiH2 active material projectile impacts on the surface of simulated satellite, the main reasons affecting electronic devices and the damage characteristics of impact products on logic chip and super-capacitor are analyzed. The experimental results show that the plasma is the main reason for interfering with the operation of logic chips and super-capacitors. When the active material projectile impacts the simulated satellite at the speed of 1.26 km/s, 1.67 km/s and 2.13 km/s, the charge and discharge time of the super-capacitor increases by 3.28 times, 4.57 times and 6 times, respectively, and the maximum operating voltage performance decreases by 12.23%, 14.44% and 18.15%, respectively. When the impact velocities are 1.67 km/s and 2.13 km/s, the output signal of the CD74HC00 chip appears transient damage due to the injection of the plasma generated by the impact, which last 0.4 ms and 1.8 ms, respectively.

Multipoint temperature measurement system composed of fiber-optic Fabry–Perot interference sensors and a wavelength-division multiplexing filter

A multipoint optical-fiber remote temperature measurement system was developed using reflection-type sensors consisting of a Fabry–Perot interference (FPI) structure with good temperature characteristics combined with a wavelength-division multiplexing (WDM) filter. The FPI sensor was fabricated using a short temperature-sensing region sandwiched between single-mode fibers. FPI optical fibers and a WDM filter functioned as the temperature sensors and wavelength-selective optical source using an amplified spontaneous emission light source, respectively. This system was operated in a dense WDM configuration using an arrayed waveguide wavelength filter.

Leaf Temperature Measurement Using Low-Resolution Thermal Camera Based on Thresholding and Clustering Techniques

Leaf temperature can indicate photosynthetic rates, leaf water status, and stomata conductance. Leaf temperature can be measured using thermal resistance sensors, thermocouple devices, infrared thermometers, or infrared thermal imaging devices. Additionally, measuring leaf temperature using a thermal camera is simple and efficient. Therefore, the research proposes a leaf temperature measurement method using AMG8833, a low-resolution (64 pixels) thermal camera. The proposed system adopts an image segmentation technique to extract the leaf area from a thermal image. The leaf temperature is then calculated by averaging the temperature values on the leaf area. The proposed system aims to utilize a low-cost and low-resolution thermal camera for measuring the leaf temperature. The proposed approach is evaluated using real images of the Dieffenbachia plant, a popular ornamental plant that can be easily planted. In the experiments, fourteen segmentation methods consisting of eight thresholding techniques and six clustering techniques are evaluated. The experimental findings on the Dieffenbachia plant indicate that the most accurate leaf temperature measurements are obtained using local thresholding with an absolute error of 0.0109 and k-means clustering with an absolute error of 0.0134. The proposed method provides a simple, effective, and low-cost leaf temperature measurement system compared to the existing systems which employ high-cost commercial thermal cameras and complex measurement methods.

Design of a Negative Temperature Coefficient Temperature Measurement System Based on a Resistance Ratio Model.

In this paper, a temperature measurement system with NTC (Negative Temperature Coefficient) thermistors was designed. An MCU (Micro Control Unit) primarily operates by converting the voltage value collected by an ADC (Analog-to-Digital Converter) into the resistance value. The temperature value is then calculated, and a DAC (Digital-to-Analog Converter) outputs a current of 4 to 20 mA that is linearly related to the temperature value. The nonlinear characteristics of NTC thermistors pose a challenging problem. The nonlinear characteristics of NTC thermistors were to a great extent solved by using a resistance ratio model. The high precision of the NTC thermistor is obtained by fitting it with the Hoge equation. The results of actual measurements suggest that each module works properly, and the temperature measurement accuracy of 0.067 °C in the range from -40 °C to 120 °C has been achieved. The uncertainty of the output current is analyzed and calculated with the uncertainty of 0.0014 mA. This type of system has broad potential applications in industry fields such as the petrochemical industry.

A Linearized Temperature Measurement System Based on the B-Mode of SC-Cut Quartz Crystal

A Linearized Temperature Measurement System Based on the B-Mode of SC-Cut Quartz Crystal

Expanding the applications of the wear-resistant titanium aluminum nitride thin-film to include temperature sensing

This study investigates an approach to temperature sensing by integrating Titanium Aluminum Nitride (TiAlN), originally engineered for wear and corrosion applications, as a temperature sensor within a multilayered thin film system. A nitride multilayer system was developed by physical vapor deposition (PVD) using a single four-target magnetron sputtering chamber; intermediate vacuum interruption steps were employed for masking procedures. The multilayer architecture design aimed to provide the sensor layer with mechanical protection and electrical shielding. Structural and electrical characterization of the TiAlN single layer revealed semiconductor behavior and stable electrical resistance up to 750 °C, with minimal signal stabilization requirements. Despite the higher Al content, the TiAlN temperature sensor exhibited a cubic crystal structure characterized by diffuse nanolayers, resulting from a two-fold rotational deposition and target configuration. A detailed examination of the multilayer system cross-section containing the TiAlN sensor was conducted using scanning transmission electron microscopy (STEM). The analysis revealed its columnar morphology with the presence of typical PVD growth defects, including voids and droplets. While the presence of these defects may impact the electrical characteristics of the sensor, the selected experimental conditions effectively maintained the structural integrity of the multilayer system despite the vacuum interruptions caused by masking procedures. Validation experiments confirmed the functionality of the multilayer system for temperature measurements up to 400 °C. The signal acquisition system addressed room temperature resistance variations and low sensitivity (thermistor coefficient ∼100 K), resulting in a measured error of approximately 6%. This study demonstrates promising results of TiAlN as a temperature sensor within a multilayered system, expanding its range of potential applications.

Multipoint Temperature Measurement System for Aero-Engine External Piping Based on Arrayed Fiber Bragg Grating Temperature Sensors

Multipoint Temperature Measurement System for Aero-Engine External Piping Based on Arrayed Fiber Bragg Grating Temperature Sensors