Temperature Measurement Method Research Articles

Diagnostic Accuracy of Three Methods of Body Temperature Measurement in Children: A Latent Class Approach

Diagnostic Accuracy of Three Methods of Body Temperature Measurement in Children: A Latent Class Approach

What is the Difference Between the Different Types of Thermometers?

Objective: There is no widely accepted method that can reflect the core temperature exactly. The aim of this study is to investigate the accuracy of frequently used body temperature measurement methods. Materials and Methods: A total of 104 patients aged 3-9 years were included in this cross-sectional study. The body temperature was measured using a non-contact cutaneous thermometer (NCCT), tympanic thermometer (TT), temporal artery thermometer (TAT), and electronic oral thermometer. Four consecutive measurements each with a different technique were taken from each patient. The oral thermometer was accepted as the reference body temperature measurement method and an oral body temperature measurement of ≥37.8°C was accepted as fever. Results: The NCCT and TT provided lower body temperature results than the oral measurement, while the TAT measured body temperatures higher than the oral thermometer. In patients whose temperature was measured as <37.8°C orally, the oral and TT measurements showed a strong positive association, while the other methods showed a weak positive association with the oral thermometer. In patients with fever, the oral and TT, and the oral and NCCT had a strong positive association while the oral thermometer and TAT had a moderate positive association. The result provided by the ROC analysis that was performed to determine the fever cut-off value for NCCT was 37.4°C, 37.7°C for TT, and 38°C for TAT. Conclusion: None of the peripheral measurement methods can accurately measure the core temperature. However, the results can be interpreted more accurately if the characteristics of the thermometers are well known.

The effect of muscle warm-up on voluntary and evoked force-time parameters: A systematic review and meta-analysis with meta-regression.

While muscle contractility increases with muscle temperature, there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and testing combinations available. Therefore, the objective of the current study was to determine the effects of different warm-up types (active, exercise-based vs. passive) on muscle function tested using different activation methods (voluntary vs. evoked) and performance test criteria (maximum force vs. rate-dependent contractile properties), with consideration of warm-up task specificity (specific vs. non-specific), temperature measurement method (muscle vs. skin), baseline temperatures, and subject-specific variables (training status and sex). A systematic search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Cochrane, Embase, and ProQuest. Random-effects meta-analyses and meta-regressions were used to compute the effect sizes (ES) and 95% confidence intervals (95%CI) to examine the effects of warm-up type, activation method, performance criterion, subject characteristics, and study design on temperature-related performance enhancement. The search yielded 1272 articles, of which 33 met the inclusion criteria (n = 921). Increasing temperature positively affected both voluntary (3.7% ± 1.8%/°C, ES = 0.28 (95%CI: 0.14, 0.41)) and evoked (3.2% ± 1.5%/°C, ES = 0.65 (95%CI: 0.29, 1.00)) rate-dependent contractile properties (dynamic, fast-velocity force production, and rate of force development (RFD)) but not maximum force production (voluntary: -0.2% ± 0.9%/°C, ES = 0.08 (95%CI: -0.05, 0.22); evoked: -0.1% ± 0.8%/°C, ES = -0.20 (95%CI: -0.50, 0.10)). Active warm-up did not induce greater enhancements in rate-dependent contractile properties (p = 0.284), maximum force production (p = 0.723), or overall function (pooled, p = 0.093) than passive warm-up. Meta-regressions did not reveal a significant effect of study design, temperature measurement method, warm-up task specificity, training status, or sex on the effect of increasing temperature (p > 0.05). Increasing muscle temperature significantly enhances rate-dependent contractile function (RFD and muscle power) but not maximum force in both evoked and voluntary contractions. In contrast to expectation, no effects of warm-up modality (active vs. passive) or temperature measurement method (muscle vs. skin) were detected, although insufficient data prevented robust sub-group analyses.

Electron temperature measurement from neutral atomic tungsten emission line ratio.

A method to determine electron temperature within a plasma by the spectral analysis of atomic tungsten emission has been explored. The technique was applied to a post-discharge region immediately following a high voltage nanosecond pulsed discharge in air with tungsten electrodes. Atomic tungsten lines are readily observed in the weak emission spectrum within the post-discharge region for many microseconds. Intensity ratios were measured at various times after the pulsed discharge for a select pair of neutral tungsten emission lines at 400.88 and 401.52nm, where the upper electronic levels of each transition are at 3.46 and 5.52eV respectively. This significant difference in upper state energy causes their line intensity ratio to vary as the electron temperature changes. In addition to the emission spectra, the absolute electron temperature could be accurately measured in our lab using laser Thomson scattering to calibrate the new tungsten emission line intensity ratio method. An analysis is presented that calculates electron temperature from these tungsten emission data assuming a Maxwellian electron energy distribution contributing to direct electron impact excitation to the upper states of each transition. The results included the derivation of a calibration factor between the two experimental methods representing a previously unreported ratio of Einstein A coefficients for the 400.88-401.52nm transitions. This derivation provides a method for future measurement of absolute electron temperature by the 400.88-401.52nm tungsten line intensity ratio without the need for laser Thomson scattering calibration.

Combustion Temperature Measurement of the Solid Propellant Specimen by Colorimetric Radiation Image

This paper investigates the influencing factors of the colorimetric radiation image temperature measurement method, including the representative wavelength, the calibration method, and the camera exposure time. A relatively high-precision method is next obtained for selecting a representative wavelength and calibration method. Then it is applied to the measurement of the combustion temperature of the solid propellant specimen. Finally, the temperature variation regularity of a different propellant was analyzed in the process of combustion. The results show that selecting the maximum response of each channel of the camera as the representative wavelength and the function construction method is more accurate for calibration and calculation. In the range of the photoelectric response of the camera, the exposure time has little effect on the temperature measurement accuracy. Compared with thermocouple temperature measurement results, the relative deviation of radiation image thermometry is −1.2%, which verifies the accuracy of radiation image thermometry.

Crystal-optical and fiber-optic temperature measurement methods: technologies and prospects

Crystal-optical and fiber-optic temperature measurement methods: technologies and prospects

Modular Light-Emitting Diode Shelving Systems for Scalable Optogenetics.

Optogenetic experiments rely on the controlled delivery of light to diverse biological systems. Impressive devices have been recently developed to stimulate cells and small animals with multiple wavelengths and intensities. However, existing hardware solutions are often limited to a single sample holder, and their design and cost can further limit scalability. This chapter describes an illumination system that is modular (through the use of accessible components) and scalable (through a shelving structure and low cost). Assembly and operation require no or minimal electrical engineering or programming expertise. Multi-intensity wavelength and temporal experiments can be performed in dozens of small and large samples. This chapter also introduces methods for temperature and light intensity measurements toward appropriate illumination conditions. This work aims to provide a greater level of accessibility and complementary opportunities for large-scale optogenetics in a broad range of biological samples.

Donor–Acceptor Structure Induced Long‐Persistent Luminescence and Application in Temperature Measurement at Cryogenic Environment

AbstractWith the development and application of cryogenic technology, the demand for temperature measurement in cryogenic environment is increasing. Optical sensing can provide a non‐contact method of temperature measurement in cryogenic environments. Herein, a new temperature measurement route based on the persistent luminescence is proposed. The single‐component, coordination crystal Zn‐ddcphpy with electron donor and acceptor structures, achieving persistent luminescence (6–7 s) after irradiating by ultraviolet light source at 80 K. The persistent luminescence decay and electron paramagnetic resonance show that the reason for the persistent luminescence generation is the photogenerated charge separation and recombination. In cryogenic environment controlled by liquid nitrogen (80–260 K), the persistent luminescence duration decreases with increasing temperature, the color gradually changes from green to yellow with the spectrum red‐shift. Taking Zn‐ddcphpy as a model material, the unquiet temperature sensitive based persistent luminescence shows convenience, intuitive and inexpensive. Furthermore, the LPL (long‐persistent luminescence) of Zn‐ddcphpy exhibits high sensitivity and responsiveness to temperature at cryonic environment, make it suitable for temperature measurement on real time. In this work, the change of duration and color can indicate temperature without contact, which can be used for temperature measurement and monitoring in the fields of cryogenic wind tunnels, cold chain storage, etc.

Compact non-contact temperature measurement device for high-intensity microwave electromagnetic fields conditions

The practical implementation aspects of heated in microwave electromagnetic fields objects noncontact temperature measurement as one of the main factors in ensuring the quality of the heat-treated product are considered. The advantages of using the pyrometric method of temperature measurement in comparison with the thermocouple method under the influence of high-intensity electromagnetic fields are substantiated. A variant, which includes a cut-off waveguide with fasteners and a small-sized infrared sensor, for continuous temperature measurement system technical implementation of heated in a microwave field objects is proposed. The variants of proposed compact, cheap and versatile temperature measurement unit using a single-zone infrared sensor of the MLX90614 family, in application to conveyor microwave heating installations are described. The convenience of embedding the sensor into the microwave technological installation control system is noted due to the presence of programming functions for the emissivity of the measured object, the possibility of transmitting information about the object temperature using one of two digital protocols, as well as the possibility of building a network of several dozen measuring sensors on one two-wire digital data bus. The small size and weight, simplicity and relative cheapness of the contactless temperature measurement unit design allows it to be used in all types of microwave heating devices.

A High-Precision Real-Time Temperature Acquisition Method Based on Magnetic Nanoparticles.

The unique magnetothermal properties of magnetic nanoparticles enable the development of a high-precision, real-time, noninvasive temperature measurement method with significant potential in the biomedical field. Based on a low-frequency alternating magnetic field excitation model, we construct two additional magnetic field excitation models-alternating current-direct current superposition and dual-frequency superposition-to extract harmonic amplitude components from the magnetization response. To increase the accuracy of harmonic information acquisition, the effects of the truncation error, excitation magnetic field frequency, and amplitude are thoroughly analyzed, and optimal parameter values are selected to minimize the error. A single algorithm is designed for temperature inversion, and a joint algorithm is proposed to optimize the performance of the single algorithm. Under low-frequency alternating-current magnetic field excitation, the autonomous group particle swarm optimization method achieves superior real-time performance in terms of temperature inversion and running time. Compared with the opposition learning gray wolf optimizer and particle swarm optimization-gray wolf optimization, the proposed method achieves reductions of 52% and 68%, respectively. Additionally, under dual-frequency superimposed magnetic field excitation, a higher temperature inversion accuracy is achieved compared with that of the particle swarm optimization-gray wolf optimization algorithm, reducing the error from 0.237 K to 0.094 K.

REGULARITIES OF THE COMBUSTION PROCESS OF METALLIC FUEL PARTICLES IN THE DECOMPOSITION PRODUCTS OF PYROTECHNIC MULTICOMPONENT NITRATE-METALLIZED MIXTURES

Purpose. The analysis and identification of regularities of the combustion process of magnesium particles in active gaseous products of thermal decomposition of nitrate-containing oxidizers and additives of the specified substances for determining the fire-hazardous properties of pyrotechnic mixtures under external thermal conditions . Methods. Modern methods of physical and chemical analysis: thermocouple methods of temperature measurement (tungsten-rhenium thermocouples were used); non-contact methods of recording the beginning and end of the burning of metal particles (temperature indicators, photosensitive elements, etc.); film shooting methods (film camera “Konvas-auto” (shooting speed 30 frames/s)) and methods of micro-filming SKS-1M film camera (shooting speed 3000…5000 frames/s)) of the burning process of individual metal particles; methods of X-ray structural and micro-X-ray spectral analysis (MRSA) for chemical analysis. The results. Data on the combustion of magnesium particles in active gaseous products of thermal decomposition of nitrate-containing oxidizers, organic and inorganic substances are systematized and summarized. It was found that the combustion of magnesium particles is highly complex, occurring through a diffusion mechanism influenced by a variety of factors. Additionally, the combustion of magnesium ribbons in a mixture of oxygen and inert gases occurs in eight distinct regions, each with characteristic flame features that depend on oxygen concentration and external pressure. It was established that magnesium particles burn in oxygen-containing media in the diffusion mode with the formation of a bright glow zone, the radius of which increases with increasing oxygen concentration and external pressure. Scientific novelty. For the first time, regularities of the combustion process of magnesium particles in active gaseous products were established (О2, О2 + N2, air, СО2, water vapor, etc.) thermal decomposition of nitrate-containing oxidants (О2, О2 + N2, air, СО2, water vapor etc.) and additives of organic substances (paraffin, stearin, iditol, thiocol, etc.) and inorganic substances (metal fluorides and oxides, etc.) to determine the fire-hazardous properties of pyrotechnic mixtures under conditions of external thermal effects. Practical significance. The theoretical and experimental results, presented as mathematical models and a database of experimental data, demonstrate the influence of technological parameters of mixture charges on the critical modes of explosive combustion under external thermal conditions (elevated temperatures, external pressures, etc.). These results enable the optimization of technological parameters (e.g., component ratios, dispersion of metallic fuel) during product manufacturing, increasing ignition temperatures and reducing the likelihood of fire-explosive destruction during storage, transportation, and product use under thermal conditions. Key words: pyrotechnic multi-component nitrate-metallized mixtures, fire safety, metal fuels, combustion processes.

Junction temperature measurement method for SiC MOSFETs based on gate internal resistance

Junction temperature measurement method for SiC MOSFETs based on gate internal resistance

Optimization of Temperature Measurement Method for High-Pressure Gas Flow Standard Facility Based on Sonic Nozzle Array

To improve the accuracy of the wind tunnel test, relying on the high-pressure gas source of the China Aerodynamic Research and Development Center, a secondary flow standard facility based on a sonic nozzle array was developed, with a pressure range of (1~6) MPa and a flow range of (0.12~5.55) kg/s. Currently, most facilities use the average temperature measured by the temperature array to represent the upstream temperature of the sonic nozzle array. However, the small flow calibration test results showed that the maximum temperature difference upstream of the standard sonic nozzle array was 1.97 K, and the temperature field upstream of the sonic nozzle array showed non-uniformity, so the above method cannot accurately obtain the upstream temperature. To solve this problem, each nozzle used in the standard sonic nozzle array was accurately measured by temperature sensors. The uncertainty of the facility and the discharge coefficient of the calibrated nozzle between the two methods were compared. The results showed that compared with the discharge coefficient obtained using the temperature sensor array of 0.9902, the accurate measurement of 0.9904 was closer to the National Institute of Metrology, China (NIM) traceable result of 0.9907, and the relative uncertainty of the facility was reduced from 0.124% (k = 2) to 0.120% (k = 2).

Rapid fatigue limit estimation of smart polymer-matrix composite under self-heating bending tests using an innovative automatic approach: Knee method

In recent years, Polymer-Matrix Composites (PMCs) have gained increasing attention across various sectors. With this growing interest and usage, accurately determining their mechanical properties, including the fatigue properties, has become crucial. Traditional methods for these evaluations are both time-consuming and costly, prompting the development of easier and more cost-effective methods for rapidly estimating the fatigue limits of materials. Among these methods, the self-heating test has emerged as notable. The first innovation of this study lies in determining the fatigue limit through the capacitance measurements of in-situ piezoceramic transducers during the four-point self-heating bending test. This determination was validated using the classical temperature measurement methods. Additionally, a novel method called the “knee method” was developped and employed, representing the second originality of this study, and it has shown very promising results.

Temperature Measurement of Ballistic Evaluation Motor Using K-Type Thermocouple

The paper presents an investigation of the burning rate of the selected solid propellant using a Ballistic Evaluation Motor (BEM) for solid-rocket propulsion study. A K-type thermocouple was used to capture the temperature of the BEM. Previous studies on BEM have been customized to specific experiments accordingly without any standardized approach for temperature measurement. Variations in the methodology have led to inconsistent and potentially unreliable results across different research efforts. The purpose of the study is to establish a more reliable and standardized method for temperature measurement in BEM by validating the temperature readings recorded by a K-type thermocouple. The scope of the study includes recording the ignition and combustion temperature of the BEM against the time. Three different propellants were used in the experiments, ammonium perchlorate with sorbitol and magnesium, potassium nitrate with sucrose, and ammonium perchlorate with sorbitol and iron (III) oxide. The results indicate that ammonium perchlorate with sorbitol gives the highest maximum temperature which is at 101℃. The other propellants, ammonium perchlorate with magnesium and potassium nitrate with sucrose, recorded maximum temperatures of 75.20 °C and 57.25 °C, respectively. The validation process confirmed the reliability of the K-type thermocouple, with an average deviation of 2.3 °C to 3.7 °C from the reference thermometer readings. A notable performance was observed for the propellant using sorbitol andammonium perchlorate with iron (III) oxide. The experiment contributes to significant findings of the solid-rocket propulsion study, hence advanced solidrocket research can be explored from here onwards.

Relationship between high-level color features and temperature mapping of magnesium alloy surface images based on the K-nearest neighbor algorithm

Numerous deformation and processing application scenarios of magnesium alloy sheets require high precision and efficiency in temperature detection. Traditional contact temperature measurement and infrared thermal imaging temperature measurement methods suffer from low accuracy and susceptibility to environmental influences. To this end, a real-time sensing method for determining the average surface temperature of magnesium alloys using visible light images is proposed in this paper. Firstly, real-time surface images of 3 mm thick magnesium alloy sheets were captured as the temperature decreased from 450 °C to 300 °C under varying light intensities. Then, calculate the high-level color features based on the grayscale frequency of the Red Green Blue color space of the image, and select the high-level color features with a strong correlation with temperature by Fisher criterion. Finally, a mapping relationship between the high-level color features of magnesium alloy images and temperature was established using the K-nearest neighbor algorithm. The results show that images in RAW format have a wider grayscale range compared to JPG, which is helpful in determining the mapping relationship between image color features and temperature. After extracting and selecting the high-level color features that have a strong correlation with temperature, the dimensions of input features are reduced. Using the K-nearest neighbor algorithm can fit the complex nonlinear relationship between high-level color features and temperature more accurately.

Experimental study of performance enhancement in PEMEC with titanium mesh flow structure via in-situ temperature measurement

A proton exchange membrane electrolysis cell (PEMEC) is a promising method for hydrogen production. However, the flow-field structure of PEMEC presently has the disadvantages of poor fluidity and uneven heat distribution. A titanium mesh flow field was, therefore, proposed to replace the traditional parallel channel structure. A single-cell test platform was set up in this study, and a new in situ temperature measurement method was proposed. The temperature variation and electrolysis performance of titanium mesh structures were studied experimentally. The results demonstrated that the polarization performance of the titanium mesh structure was enhanced compared to that of the parallel structure. In situ measurements showed that the temperature increased and the voltage decreased with an increase in the inlet temperature and flow rate, with the rate of change gradually decreasing. The temperature distribution in the titanium mesh structure was more uniform than that in the parallel structure. When the current density and inlet flow rate step were changed, the voltage stabilized within 12 s. After 100 h of operation, the voltage of the parallel structure and titanium mesh structure increased by 0.12 V and 0.07 V, respectively, indicating good dynamic and duration performance.

Development of a DualEmission Laser-Induced Fluorescence (DELIF) Method for Long-Term Temperature Measurements.

The fluorescence intensity of fluorescent dyes typically employed in the dual-emission laser-induced fluorescence (DELIF) method gradually degrades as the excitation time increases, and the degradation rate depends on the type of fluorescent dye used. Therefore, the DELIF method is unsuitable for long-term temperature measurements. In this study, we focused on the fluorescence intensity ratio of a single fluorescent dye at two fluorescence wavelengths and developed a DELIF method for long-term temperature measurements based on this ratio. The fluorescence intensity characteristics of Fluorescein disodium and Rhodamine B, which are typically used in the DELIF method, in the temperature range of 10-60 °C were comprehensively investigated using two high-speed monochrome complementary metal-oxide semiconductor cameras and narrow bandpass filters. Interestingly, the ratio of the fluorescence intensity of each fluorescent dye at the peak emission wavelength of the fluorescence spectrum, λ, to the fluorescence intensity at wavelengths very close to the peak wavelength (λ ± 10 nm) was highly sensitive to temperature variations but not excitation time. Particularly, when Rhodamine B was used, the selection of the fluorescence intensity ratios at a wavelength combination of 589 and 600 nm enabled highly accurate temperature measurements with a temperature resolution of ≤0.042 °C. Moreover, the fluorescence intensity ratio varied negligibly throughout the excitation time of 180 min, with a measurement uncertainty (95% confidence interval) of 0.045 °C at 20 °C. The results demonstrate that the proposed DELIF method enables highly accurate long-term temperature measurements.

Research on Multispectral Brightness Temperature Measurement Method Based on Computational Spectral Splitting

Research on Multispectral Brightness Temperature Measurement Method Based on Computational Spectral Splitting

Temperature measurement method with line and continuum emissions in Ar-N2 DC arc

This study discusses a technique for accurate temperature measurement of thermal plasmas with a high-speed camera. The temperature of thermal plasmas is an important parameter for plasma processes. High-speed cameras are useful to measure plasma temperatures in two dimensions. Measurements of plasma emission with a high-speed camera and band-pass filter provide only the spectral intensity of the entire transmitted wavelength range. Temperature measurements with high-speed cameras by the Boltzmann plot method or Fowler⎯Milne method are less accurate. Theoretical consideration of the line and continuum emissions has improved the accuracy of plasma temperature measurement. The measurement target was a free-burning arc in an argon and nitrogen atmosphere. Temperature errors were estimated based on the deviation from the true emission coefficient. The calculation and measurement errors were discussed as the factors of the deviation. Error estimation provides important insight into the selection of the measurement wavelength.