Thermometry Method Research Articles

Isotope radon measurement method to identify spontaneous combustion regions in coal gangue hills: case study for a coal mine in China

ABSTRACT Long-term accumulation of coal gangue hill has a high risk of spontaneous combustion, and the toxic and harmful gases emitted by spontaneous combustion seriously pollute the atmosphere. The key to managing the spontaneous combustion fire of coal gangue hill lies in the accurate measurement of fire source location. However, measuring the fire source location of surface coal gangue hill lacks experimental and empirical research. In this paper, an oxidation warming experiment was conducted on the coal gangue samples, and the law of radon gas exhalation from coal gangue under different temperatures was analyzed. At the same time, surface thermometry and isotope radon measurement were applied to measure the high-temperature areas inside the gangue hill, and the measurement results were compared. The experimental results show that as the temperature of gangue increases, the amount of radon gas exhalation in gangue shows a changing trend of rising first and then decreasing. The radon exhalation from coal gangue can be divided into three stages. In the I stage (30 ~ 100°C), the evaporation of pore water in coal gangue leads to the exhalation of radon in water, causing the increase of radon concentration; in the II stage (100 ~ 350°C), the coal gangue is pyrolyzed at high temperature, and a large amount of radon is exhalated from the closed pores; in the III stage (350 ~ 450°C), after the first two stages of radon release, the number of radon atoms in this stage decreases, leading to a rapid decrease of radon concentration. The field measurement results show that compared with the surface thermometry method, the isotope radon measurement method is less disturbed by external conditions, and the circled fire area is more accurate, which has essential theoretical significance and practical application value for the accurate measurement of fire source location in coal gangue hill.

Multi-echo MR thermometry in the upper leg at 7T using near-harmonic 2D reconstruction for initialization.

The aim of this work is the development of a thermometry method to measure temperature increases in vivo, with a precision and accuracy sufficient for validation against thermal simulations. Such an MR thermometry model would be a valuable tool to get an indication on one of the major safety concerns in MR imaging: the tissue heating occurring due to radiofrequency (RF) exposure. To prevent excessive temperature rise, RF power deposition, expressed as specific absorption rate, cannot exceed predefined thresholds. Using these thresholds, MRI has demonstrated an extensive history of safe usage. Nevertheless, MR thermometry would be a valuable tool to address some of the unmet needs in the area of RF safety assessment, such as validation of specific absorption rate and thermal simulations, investigation of local peak temperatures during scanning, or temperature-based safety guidelines. The harmonic initialized model-based multi-echo approach is proposed. The method combines a previously published model-based multi-echo water/fat separated approach with an also previously published near-harmonic 2D reconstruction method. The method is tested on the human thigh with a multi-transmit array at 7T, in three volunteers, and for several RF shims. Precision and accuracy are improved considerably compared to a previous fat-referenced method (precision: 0.09 vs. 0.19°C). Comparison of measured temperature rise distributions to subject-specific simulated counterparts show good relative agreement for multiple RF shim settings. The high precision shows promising potential for validation purposes and other RF safety applications.

Magnetic Nanoparticle Thermometry via Controlled Diffusion

The process of magnetic nanoparticle heating releases enormous amounts of thermal energy. Through typical calorimetric analyses, the total thermal energy released can be easily quantified; however, knowledge of nanoscale temperature is necessary. Herein, a novel method of nanoscale thermometry by analyzing intra-particle diffusion in core–shell nanoparticles is proposed. Heating the iron cores with an alternating magnetic field in a saline suspension encourages the diffusion of sodium ions into the silica shells of the particles, which is modeled numerically; however, experimental measurements are needed in order to provide accurate diffusivity estimations. After determining the diffusion characteristics from X-ray photoelectron spectroscopy) depth profiling of silica films, energy dispersive analysis with high-resolution transmission electron microscopy measures the sodium ion gradient within single particles before and after heating. When compared directly to the numerical simulations, the results indicate that the temperature gradient between particles and saline suspension reaches significantly higher temperatures than the macro-scale temperature of the solution. By accurately knowing the thermal gradient between nanoparticles and the surrounding medium, nanoparticles can be engineered to limit surface resistances as much as possible and promote high rates of thermal energy transfer.

Core temperature measurement using ultrasound for high precision manufacturing processes

During machining processes, the temperature of the workpiece may vary due to different factors. One of such factors is the heat generated due to tool/workpiece friction. Temperature may also vary due to environmental conditions. These temperature variations can affect the dimensional accuracy of the manufactured workpiece. It is known that the expansion of a part is related to a change in its average temperature, which is influenced more by the internal, core temperature than the surface temperature. The surface temperature of the part being manufactured can vary significantly from the core temperature, especially during dry cutting processes. Therefore, to effectively control or compensate for the effects of temperature variation as it relates to material expansion, there is a need to measure the core temperature of the workpiece accurately. In this article, a novel ultrasonic phase-shift method for temperature measurement is used to measure the core temperature of a workpiece on a computer numerical control machine (CNC). The results show that the phase-shift ultrasonic thermometry method measures steel workpiece temperature during subtractive manufacturing processes with deviations of less than ±1°C when compared to the reference PT100 readings. This novel temperature measurement method can be used in different manufacturing processes as part of a temperature control or thermal error compensation system.

Study of soft wheat by the canopy temperature depression under Altai territory conditions

Results of research in the field of wheat drought tolerance breeding by infrared thermometry method are presented. It is noted that in Russia this method is still not widespread. The parameter Canopy temperature depression (CTD) among collection samples of spring wheat was studied. The experiment was conducted in the Altai Territory in 2019-2021. Yield, elements of its structure and the duration of seedling – heading period were studied in 55 varieties of spring soft wheat. The canopy temperature was measured with a portable infrared thermometer. CTD was defined as the difference between the air temperature and the canopy temperature. The average CTD across the varieties was 6.1, -0.8, and 2.6 °C in 2019, 2020, and 2021, respectively. Significant influence on the variability of this trait had both the factor of year and genotype. During the three years of the study CTD had a stable reliable relationship with the duration of the seedling - heading period (r = 0.27- 0.37), and in two of the three years - with the yield (r = 0.32 and 0.60). In the driest year (2020), CTD was positively correlated not only with the yield structure elements (r = 0.17-0.48), but also with the plant height (r = 0.55). The highest average CTD value for three years was recorded for Altayskaya zhnica (3.5 °C), Stepnaya niva (3.6 °C), Burlak (3.8 °C), Obskaya 2 (3.9 °C), Lutescens 360/96, Merzana, Alexander (4.0 °C) and Lutescens 208/08-4 (4.4 °C) cultivars.

Analytical models of induction heating of casing in a producing well

The article is devoted to the study of heat exchange processes in a well during induction heating of metal casing section. Heating of the column leads to an increase in the temperature of the fluid flow in the column. Due to short-term exposure, heat marks appear in the flow. Observation of their evolution forms the basis of active thermometry, a new method in borehole geophysics. Analytical solutions have been obtained for calculating the temperature changes of the upstream and casing during induction heating. Analytical solutions are compared with numerical simulation in Ansys Fluent*. It is shown that the discrepancy between the results of calculations based on analytical and numerical models decreases with an increase in the Reynolds number and the transition to a turbulent flow regime, with active mixing of the flow in the well in it is cross section. The developed models will be used in the planning of geophysical studies in wells by the method of active thermometry. Keywords: active thermometry; borehole; induction heating; column temperature; Nusselt number; Laplace transformations.

Convolutional neural networks open up horizons for luminescence thermometry

Luminescence thermometry has emerged as an effective way to implement non-invasive thermal reading and finds promising applications in many fields. Nevertheless, traditional luminescence thermometric methods, such as the luminescence intensity ratio, are generally carried out based on one single temperature-dependent spectral feature. As a result, other thermal related spectral features were ignored, which radically restricts the sensing performance. Herein, we preliminarily propose a novel strategy for driving luminescence thermometry via convolutional neural network. The trained network is able to autonomously select and extract multiple temperature-dependent features for regression temperature, so the temperature-dependent spectral data can be fully utilized. Using Y3Al5O12: Cr3+ as the temperature sensing material, the proposed thermometry method exhibits high accuracy and strong generalization over the additional test set. The maximum measurement error (emax) in the range of 35–315 °C is about 0.77 °C, accompanied with the average error (eaver) of 0.20 °C. The accuracy of the proposed approach is significantly superior to those achieved by the classical ratiometric technology (emax≈4.05 °C, eaver ~ 1.31 °C) and the widely used multiple linear regression method (emax≈4.27 °C, eaver ~ 1.69 °C), indicating deep learning has the potential to open up a new era of luminescence thermometry.

Measurement of Mass Transfer Intensity in Gas–Liquid Medium of Bioreactor Circuit Using the Thermometry Method

The development of energy-efficient solutions for large-scale fermenters demands a deep and comprehensive understanding of hydrodynamic and heat and mass transfer processes. Despite a wide variety of research dedicated to measurements of mass transfer intensity in bubble flows, this research subject faces new challenges due to the topical development of new innovative bioreactor designs. In order to understand the fluid dynamics of the gas–liquid medium, researchers need to develop verified CFD models describing flows in the bioreactor loop using a progressive physical and mathematical apparatus. In the current paper, we represent the results of evaluating the key performance indicator of the bioreactor, namely the volumetric mass transfer coefficient (kLa) known as a parameter of dominant importance for the design, operation, scale-up, and optimization of bioreactors, using the developed thermometry method. The thermometry method under consideration was examined within a series of experiments, and a comparative analysis was provided for a number of various regimes also being matched with the classical approaches. The methodology, experiment results, and data verification are given, which allow the evaluation of the effectiveness and prediction of the fluid flows dynamics in bioreactors circuits and ultimately the operational capabilities of the fermenter line.

Ultra-sensitive luminescence ratiometric thermometry from 2E→4A2 transitions of AlTaO4:Cr3.

In recent years, non-contact ratiometric luminescence thermometry has continued to gain popularity among researchers, owing to its compelling features, such as high accuracy, fast response, and convenience. The development of novel optical thermometry with ultrahigh relative sensitivity (Sr) and temperature resolution has become a frontier topic. In this work, we present a novel, to the best of our knowldege, luminescence intensity ratio (LIR) thermometry method that relies on AlTaO4:Cr3+ materials, based on the fact that they possess both anti-Stokes phonon sideband emission and R-line emission at the 2E→4A2 transitions and have been confirmed to follow the Boltzmann distribution. In the temperature range 40-250 K, the emission band of the anti-Stokes phonon sideband shows an upward trend, while the bands of the R-lines show the opposite downward trend. Relying on this fascinating feature, the newly proposed LIR thermometry achieves a maximum relative sensitivity of 8.45%K-1 and a temperature resolution of 0.038 K. Our work is expected to provide guiding insights for optimizing the sensitivity of Cr3+-based LIR thermometers and provide some novel entry points for designing excellent and reliable optical thermometers.

Nanoscale thermometry under ambient conditions via scanning thermal microscopy with 3D scanning differential method.

Local temperature measurement with high resolution and accuracy is a key challenge in nowadays science and technologies at nanoscale. Quantitative characterization on temperature with sub-100nm resolution is of significance for understanding the physical mechanisms of phonon transport and energy dissipation in nanoelectronics, optoelectronics, and thermoelectric devices. Scanning thermal microscopy (SThM) has been proved to be a versatile method for nanoscale thermometry. In particular, 2D profiling of the temperature field on the order of 10nm and 10 mK has already been achieved by SThM with modulation techniques in ultrahigh vacuum to exclude the parasitic heat flow between air and the cantilever. However, few attempts have been made to truly realize 2D profiling of temperature quantitatively under ambient conditions, which is more relevant to realistic applications. Here, a 3D scanning differential method is developed to map the 2D temperature field of an operating nanodevice under ambient environment. Our method suppresses the thermal drift and the parasitic heat flow between air and the cantilever by consecutively measuring the temperatures in thermal contact and nonthermal contact scenarios rather than in a double-scan manner. The local 2D temperature field of a self-heating metal line with current crowding by a narrowing channel is mapped quantitatively by a sectional calibration with a statistic null-point method and a pixel-by-pixel correction with iterative calculation. Furthermore, we propose a figure of merit to evaluate the performance of thermocouple probes on temperature field profiling. The development of nanoscale thermometry under ambient environment would facilitate thermal manipulation on nanomaterials and nanodevices under practical conditions.

Laser Method for Studying Temperature Distribution within Yb:YAG Active Elements

Currently, laser systems based on active elements doped with Yb3+ with simultaneously high pulse repetition rates and high peak power are in demand for many applications. High thermal load of active elements is the primary limiting factor for average power scaling. Experimental investigation of temperature distribution in active elements is of particular importance for estimation of cooling efficiency and for thermal processes’ monitoring. In the present work, the method of dynamic laser thermometry is proposed for temperature distribution investigation within cryogenically cooled Yb3+-doped active elements. The method is based on the dependence of the Yb3+ ion absorption cross-section on temperature at a wavelength of 1030 nm. The method was tested to study the 2D temperature map of the Yb:YAG active element of the high-power, diode-pumped, cryogenically cooled laser amplifier. The best measurement accuracy ±3 K is achieved at the maximal temperature 176 K. The results of numerical simulation are in good agreement with the experimental data. On the basis of the investigation, the quality of the cooling system is evaluated. The advantages and other possible applications of the method are discussed.

Fast, interleaved, Look-Locker-based T1 mapping with a variable averaging approach: Towards temperature mapping at low magnetic field.

Proton resonance frequency shift (PRFS) is currently the gold standard method for magnetic resonance thermometry. However, the linearity between the temperature-dependent phase accumulation and the static magnetic field B0 confines its use to rather high-field scanners. Applications such as thermal therapies could naturally benefit from lower field MRI settings through leveraging increased accessibility, a lower physical and economical footprint, and further consideration of the technical challenges associated with the integration of heating systems into conventional clinical scanners. -based thermometry has been proposed as an alternative to the gold standard; however, because of longer acquisition times, it has found clinical use solely with adipose tissue where PRFS fails. At low field, the enhanced dispersion, combined with reduced relaxation times, make mapping an appealing candidate. Here, an interleaved Look-Locker-based mapping sequence was proposed for temperature quantification at 0.1T. A variable averaging scheme was introduced, to maximize the signal-to-noise ratio throughout recovery. In calibrated samples, an average accuracy of 85% ±4% was achieved in 10min, compared with the 77% ±7% obtained using a standard averaging scheme. Temperature maps between 29.0 and 41.7°C were eventually reconstructed, with a precision of 3.0±1.1°C and an accuracy of 1.5±1.0°C. Accounting for longer thermal treatments and less strict temperature constraints, applications such as MR-guided mild hyperthermia treatments at low field could be envisioned.

Development and validation of a hybrid constraint spectral thermometry for laminar sooting flames.

A hybrid constraint spectral thermometry (HCST) method based on combined light extinction and spectral soot emission was developed for temperature measurements in sooting flames. Light extinction measurements were performed in the 635-1064 nm spectral range to constrain the fitting of the soot optical property E(m) as a function of the wavelength for separately measured spectral emission data. This hybrid constraint methodology helps to avoid complete reliance on either measurement, which significantly increases the immunity of the temperature determination to measurement noises. After numerically validating the performance of HCST, measurements were performed for a series of representative sooting premixed flames. Additional measurements were conducted with the proven tunable diode laser absorption technique to provide a reference temperature, and satisfactory agreements demonstrate the accuracy and robustness of the proposed HCST method.

A Time-of-Flight Estimation Method for Acoustic Ranging and Thermometry Based on Digital Lock-In Filtering.

Accurate ranging and real-time temperature monitoring are essential for metrology and safety in electrical conduit applications. This paper proposes an acoustic time-of-flight (TOF) estimation method based on the digital lock-in filtering (DLF) technique for conduit ranging and thermometry. The method establishes the relationship between the frequency and the time domain by applying a linear frequency modulated Chirp signal as the sound source and using the DLF technique to extract the first harmonic of the characteristic frequencies of the transmitted and received signals. Acoustic TOF estimation in the conduit is then achieved by calculating the mathematical expectation of the time difference between each characteristic frequency in the time-frequency relationship of the two signals. The experimental results with enhanced noise interference on different conduit lengths and various temperature conditions, proved that the proposed DLF method can establish a robust linear time-frequency relationship according to the characteristics of the Chirp signal, and the measurement accuracy of TOF has also been confirmed. Compared to the conventional method, the DLF method provides the lowest absolute error and standard deviation for both distance and temperature measurements with an enhanced robustness.

Diagnostics and correction of microcirculation disorders and endothelial dysfunction in complex therapy of acute pancreatitis with antioxidant drugs

Objective. To assess the efficiency of using polypositional skin thermometry of high resolution with wavelet-analysis of the obtained curve as a screening noninvasive method for diagnostics and correction of microcirculatory disorders and endothelial dysfunction in complex therapy of acute pancreatitis using antioxidant drugs.
 Materials and methods. A prospective open randomized study of 30 patients with acute pancreatitis was carried out. The polypositional skin thermometry of high resolution with wavelet-analysis of the obtained curve was chosen as a screening method of diagnostics of microcirculatory disorders and endothelial dysfunction. Measurement of temperature oscillation amplitude with an accuracy to 0,001 С was performed in conditions of skin heating with index finger. The study was implemented before and after calf blood deproteinized hemoderivative infusion.
 Results. Reliable changes in skin temperature oscillation of the microcirculatory bed of the skin in the endothelial range on the days 1, 2 and 3 of drug infusion were detected. In the investigated group of patients, the phenomena of transitory organ dysfunction were arrested during 48 hours that proves the presence of pancreatitis of a moderate degree of severity. The temperature oscillation amplitudes of skin in neurogenic range significantly differed by the moment of arresting organ dysfunction.
 Conclusions. The method of polypositional skin thermometry of high resolution with wavelet-analysis of the obtained curve can be offered as an instrument for assessment of endothelial dysfunction prior to appearance of clinical manifestations of acute pancreatitis. The calf blood deproteinized hemoderivative infusions applied as a metabolic therapy positively influence the endothelial dysfunction in acute pancreatitis of a moderate degree of severity.

On the measurement of flame temperature and emissivity based on multispectral imaging technique

Due to the low spatial resolution of spectrometer and low spectral resolution of CCD, a multi-wavelength radiation thermometry method employing multispectral imaging technology was proposed to measure flame temperature and emissivity. The calculated radiation intensity lines were obtained by the Hottel emissivity model and the least square method. The temperature and flame absorption capacity with the calculated spectral line closest to the measured spectral line were considered as the optimum results. The experimental results showed that maximum temperature of the flame was 1943 K appeared in the thin-wick paraffin. At any position, the emissivity of the thin-wick paraffin flame was lower than that of the thick-wick, but the emissivity of the biomass candle flame near the flame center was the highest. The measured temperature distribution was validated by employing a spectrometer system and the relative error was 2.66%.

Comprehensive,in operando, and correlative investigation of defects and their impact on device performance

Abstract Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conducted in a parallel mode wherein the semiconductor wafer was divided into multiple pieces for separate optical and structural characterization, as well as device fabrication and evaluation. The major limitation of this approach was that either the defect being investigated by structural characterization techniques was not the same defect that was affecting the device performance or else the defect was not characterized under normal device operating conditions. In this review, we describe a more comprehensive approach to defect study, namely a series mode, using an array of spatially-resolved optical, electrical, and structural characterization techniques, all at the individual defect level but applied sequentially on a fabricated device. This novel sequential approach enables definitive answers to key questions, such as: (i) how do individual defects affect device performance? (ii) how does the impact depend on the device operation conditions? (iii) how does the impact vary from one defect to another? Implementation of this different approach is illustrated by the study of individual threading dislocation defects in GaAs solar cells. Additionally, we briefly describe a 3-D Raman thermometry method that can also be used for investigating the roles of defects in high power devices and device failure mechanisms.

Development of a multi-spectral thermal imager for measurement of the laser-induced damage temperature field

In order to analyze the damage effectiveness of the high-energy laser beam damage to the target, it is important to accurately measure the laser-induced damage temperature field. However, the obtained data cannot meet the requirements of damage effectiveness evaluation, as most of these data are from simulated temperature measurements in the laser-induced damage temperature field. Moreover, traditional temperature measuring instruments can only measure temperature points, and cannot obtain the multi-spectral temperature field of the laser-induced damage. In response to the above problems, this paper has developed a multi-spectral thermal imager for measurement of the laser-induced damage temperature field. Using a five-channel four-wavelength filter photometer, the instrument makes the fifth channel as a calibration channel so that the infrared thermal imager can accurately collect data under multi-spectral channels. Temperature fields corresponding to the spectral data can be inverted by multi-spectral thermometry method. The temperature results of the multi-spectral thermal imager are compared with that of thermocouples, and the measurement error is<1.5%. According to the experimental data of laser-induced damage field measurements, it is shown that the laser-induced damage temperature field can be acceptably measured with the multi-spectral thermal imager.

Luminescence intensity ratio squared—A new luminescence thermometry method for enhanced sensitivity

In response to the sensitivity limitation of ratiometric luminescence thermometers, herein we propose a novel temperature readout, which exploits two pairs of thermalized energy levels in trivalent lanthanide ion-activated phosphors, to provide significantly enhanced sensitivity. This method is called the luminescence intensity ratio squared (LIR2) method. It is a combination of the dual-excitation single emission band ratiometric (SBR) and conventional (Boltzmann) luminescence intensity ratio (LIR) techniques. The relative sensitivity of LIR2 is the sum of the sensitivities of each method, and its thermal dependence is predicted theoretically. We explain the LIR2 method in detail and identify the perspective of lanthanide-activated probes. The performance of the proposed approach was evaluated using YVO4:Eu3+ and YNbO4:Eu3+ powders and compared with those of the SBR and LIR techniques. The LIR2 method displayed significantly better thermometric performance than SBR and LIR over a wide temperature range (300–850 K).

On-line detecting the tuyere coke size and temperature distribution of raceway zone in a working blast furnace

Developing the new injection energy including full oxygen, hydrogen and natural gas injection in raceway zone of blast furnace is one of the effective and feasible measures to reducing the carbon emission and satisfying the carbon neutral plan. While the tuyere combustion condition under all-coke smelting model of blast furnace could supplying a direct manner to observing how the new energy affecting the coke combustion and temperature variety process during raceway process. In this paper, the tuyere coke particle sizes and raceway temperature distribution, as the representative parameters of raceway combustion, are online detected at the same time in a working 2500 m3 blast furnace under the all-coke smelting model by machine vision, Fully Convolutional Networks (FCN), and colorimetric thermometry method (CTM). The results showed the same ranges compared to research of coke sampling and average temperature in tuyere zone. And the calculation of coke belt length (CBL) in raceway zone by empirical model were modified to evaluate the coke combustion and size decaying under all-coke smelting model. Which could not only benefit to study the coke cracking and formation mechanism in the raceway zone in a blast furnace after the new energy injection, but also provide a new method to online detect particle size and temperature distribution at the same time in complex environment by deep learning and machine vision methods.