Infrared Temperature Measurement Research Articles

A data processing algorithm for multispectral radiation thermometry based on multi-segment linear model and secondary inversion

Multispectral radiation thermometry is a branch of infrared temperature measurement technology with wide application in many industries. Although this technology has been developed for decades, there is still a problem in its data processing, that is, how to accurately solve the radiation equations without the information of object’s emissivity. The traditional fixed emissivity model method cannot adapt to all objects. Therefore, this study proposes a data processing algorithm for multispectral radiation thermometry based on multi-segment linear model and secondary inversion. The algorithm can automatically select the multi-segment linear model suitable for the measured object, and realize the accurate calculation of temperature and emissivity through the secondary inversion. The efficiency and accuracy of the algorithm are verified through simulations. The experimental results of temperature measurement of aviation alloy prove the effectiveness of this algorithm in practical application.

Effect of multilayer anti-reflective coating on spectral emissivity of area blackbody

An area blackbody is used as a standard radiant source for calibrating equipment of non-contact infrared temperature measurement. Tailoring the spectral emissivity of area blackbody is important for improving the accuracy of a temperature measurement system. In this work, a new antireflective coating (ARC) has been proposed and the first association it with area blackbody has been made to improve the emission in the 3–14 μm wavelength range. We have compared the single, dual and triple-layer of different ARC materials with a different combination. In each category, we have optimized the SiO2, Al2O3 and Si3N4 thin films layer stack as ARC coating and then compared radiation property of area blackbody covered by ARC. Numerical simulations of the spectral emissivity of the combination reveals that double-layer ARC is taken as the most excellent stack structure, which can realize spectral emissivity exceeding 0.9 with least material in the wavelength range from 3 to 13 μm. Physical mechanisms responsible for the increasing emissivity are elucidated as due to producing the gradual variation of the refractive index and the selection of each layer material directly affects emission performance. Considering excellent radiation property of area blackbody combined with ARC, this study can help pave the way for designing ideal area blackbody.

Dynamic breakage of double glass spheres chain subjected to impacting loading

Strain energy releasing due to local failure plays an important role in the dynamic breakage of the brittle medium. A series of experiments are conducted based on the Split Hopkinson pressure bar (SHPB) device. Two contact modes, i.e. the rigid contact between two spheres and the elastic contact between the sphere and the impact/support bar, are introduced by using the double sphere chain sample. Two methods, e.g. the Infrared temperature measurement (ITMS) method and the Digital image correlation (DIC) method, are utilized to trace the fracture sequence of the chain samples under impact velocity 5.0–13.0 m/s. The effects of strain energy releasing to the force-displacement curves, the temperature rising process, and the broken products of the chain samples are demonstrated in detail. Releasing of strain energy causes a delayed recompression process, and the delayed time decreases with increasing of impact velocity, which was caused by the formation and releasing of local strain in elastic contact mode. The approaches to evaluate the effects of strain energy releasing are then proposed to analyze the force-displacement curves and the temperature rising process. The elevated temperature is estimated to be a linear relationship to ε˙2/3. It is of great significance for the profound understanding of the failure mechanism of sphere aggregates.

Regression model for predicting core body temperature in infrared thermal mass screening.

With fever being one of the most prominent symptoms of COVID-19, the implementation of fever screening has become commonplace around the world to help mitigate the spread of the virus. Non-contact methods of temperature screening, such as infrared (IR) forehead thermometers and thermal cameras, benefit by minimizing infection risk. However, the IR temperature measurements may not be reliably correlated with actual core body temperatures. This study proposed a trained model prediction using IR-measured facial feature temperatures to predict core body temperatures comparable to an FDA-approved product. The reference core body temperatures were measured by a commercially available temperature monitoring system. Optimal inputs and training models were selected by the correlation between predicted and reference core body temperature. Five regression models were tested during the study. The linear regression model showed the lowest minimum-root-mean-square error (RSME) compared with reference temperatures. The temple and nose region of interest (ROI) were identified as optimal inputs. This study suggests that IR temperature data could provide comparatively accurate core body temperature prediction for rapid mass screening of potential COVID cases using the linear regression model. Using linear regression modeling, the non-contact temperature measurement could be comparable to the SpotOn system with a mean SD of ± 0.285°C and MAE of 0.240°C.

A rapid prediction algorithm suitable to portable device for animal body-temperature measurement

The body-temperature is the most significant vital signs of human and animals. It is easily imaginable that measurement of body-temperature of animals will be much more difficult than that of human being due to lack of endurance or fear of measuring instrument. Infrared temperature measurement device may be a solution, however coverage of hair and fur may incur a large error. To address this issue, a rapidly executed algorithm is developed for prediction of steady state body temperature, which needs only a few one-tenth of measurement duration that the currently popular machine learning-based approach usually requires. Let a cubic function c⁢(t) fit the sampled temperature data which are generated by the measurement within a significantly short duration from tn-k to tn,k>0. Then let a quadratic function f⁢(t)=a2⁢t2+a2⁢t+a as a prediction function go through the point (tn,c⁢(tn)) and share the same slope of sn thereat. Finally try to find a next point (tn+m,f⁢(tn+m)), m>0, where the slope satisfies sn+m=sn/2 and m depends strongly on sn through an empirical formula. Accordingly, f⁢(t) can be determined by (tn,c⁢(tn)), sn and sn+m. Experiments indicate that the maximum of f⁢(t) approaches well the steady state temperature of the measured subject with a quite small error.

Investigation of the effective wavelength applied on the active dual wavelength infrared temperature measurement

The active dual-laser temperature measurement method has the advantages of no contact with the target surface, no need to know the emissivity information of the target to be measured in advance and strong anti-interference ability. In the active dual laser temperature measurement model, the effective wavelength value of the detector has a direct influence on the measurement results. However, the influence of detector effective wavelength on the measurement results is still not fully understood. Therefore, in this paper, the effective wavelength of the detector is introduced into the active dual-laser temperature measurement model, the migration rule of the measurement results when the response curve bandwidth changes and response curve moves is studied, and the actual measurement results are analyzed.

Short Communication: Use of Infrared Thermometers for Cutaneous Temperature Recording: Agreement with the Rectal Temperature in Felis catus.

Simple SummaryThe recording of body temperature by rectal temperature assessments is a stressful procedure for cats. For this purpose, alternative methods for using rectal digital thermometers to monitor body temperature were investigated. Skin temperature was recorded in 20 cats, in 5 different body regions, and compared with the rectal temperature. The obtained data indicated that the cutaneous temperature recorded by the infrared thermometers was not in agreement with the data recorded by the digital thermometer in the rectum.In veterinary medicine, the gold standard for assessing body temperature is rectal temperature assessment. Considering that this procedure is stressful for many species, in particular for cats, it could be clinically important to consider an alternative approach for the monitoring of core body temperature. The aim of this study was to test if cutaneous temperature measurements by means of different infrared thermometers are in agreement with the most commonly used method for body temperature measurement in cats. The cutaneous temperature was recorded in the jugular, shoulder, rib, flank, and inner thigh, using three different non-contact infrared thermometers (IR1, IR2, and IR3) in 20 cats. The cutaneous temperature was then compared to the rectal temperature, recorded by means of a digital thermometer. The obtained data indicated that the cutaneous temperature recorded by the infrared thermometers was not in agreement with the data recorded by the digital thermometer in the rectum. In cats, the use of non-contact infrared thermometers gave no reproducible or constant data to justify their application for the recording of body temperature instead of rectal temperature recording. In addition, the infrared temperature measurement devices generated results that were not in good agreement among themselves, providing a novel result of clinical importance.

A data processing method on infrared temperature measurement of non-lambert body in a non-uniform environment

Ambient temperature is one of the most important factors influencing the accuracy of infrared temperature measurement when detecting temperatures near the ambient ones. Starting from the classical ambient temperature compensation method, a data processing method on the infrared temperature measurement of a non-lambert body in a non-uniform environment is proposed. Experiments were conducted to compare the temperature measurement accuracy of the classical method and the one proposed in this paper, in a non-uniform environment. Data processing of the experiments involves parameters fitting, object emissivity measurement, and measurement of each temperature source in the environment. The experiments demonstrated the effectiveness of the proposed method, which can effectively solve the ambient interference problems when the non-lambert body (such as aluminum and steel) are present.

On the function of lead (Pb) in machining brass alloys

Lead has traditionally been added to brass alloys to achieve high machinability, but the exact mechanisms at work are still debated. Lead-free brass alternatives could be developed if these mechanisms were better understood. Accordingly, machinability characteristics were investigated for two brass alloys with similar mechanical properties and phase composition, but with very different machining characteristics because one has 3 wt.% lead (CuZn38Pb3) while the other has only 0.1 wt.% (CuZn42). The effect of the lead was investigated using infrared temperature measurement, electron microscopy, secondary ion mass spectroscopy, quick-stop methods, and high-speed filming. Neither melting of lead nor its deposition on the tool rake surface takes place during machining thus confirming its limited lubrication and tribological effects. Instead, the main role of lead is to promote discontinuous chip formation. Lead deforms to flake-like shapes that act as crack initiation points when the workpiece material passes through the primary deformation zone. This effect prevents the development of stable tool–chip contact, thus lowering cutting forces, friction, and process temperature.

Influence of preheating temperature and printing speed on interlaminar shear performance of laser‐assisted additive manufacturing for CCF/PEEK composites

AbstractContinuous carbon fiber reinforced poly‐ether–ether–ketone (CCF/PEEK) shows great potential in engineering applications attributed to superior mechanical properties together with excellent thermal and chemical resistance. In this study, a laser‐assisted additive manufacturing device was established to accurately collect and control the preheating temperature based on a coaxial infrared temperature measurement system. The influence on laser power consumption, interlaminar shear performance, and failure mechanism was investigated in condition of different preheating temperatures and printing speeds. Results indicated that the laser‐preheated specimens showed much higher ILSS with maximum values and increasing percentage reached 33.48 MPa and 157.0% compared to unpretreated specimens. With the increase of preheating temperature and printing speed, more laser power was consumed, while the ILSS and increasing percentage increased firstly and then decreased. The strengthening effect on the interlayer bonding was ascribed to promoting the penetration of PEEK molecular chain ends between adjacent layers, increasing the fluidity and enhancing the bonding effect between adjacent filament together with improving the impregnation behavior of the inner fibers. The proposed interlaminar strengthening method based on laser‐assisted preheating provides potential application prospects in aerospace and automotive industries.

Ignition and Combustion Characteristic of B·Mg Alloy Powders.

Boron and its alloys have been explored a lot and it is expected that they can replace pure aluminum powder in the energetic formulation of active materials. MgB2 compounds were prepared and characterized by a combination of mechanical alloying and heat treatment. The ignition and combustion of boron–magnesium alloys were studied with the ignition wire method and laser ignition infrared temperature measurement. The results show that MgB2 has good ignition characteristics with maximum ignition temperatures obtained by the two various methods of 1292 K and 1293 K, respectively. Compared with boron, the ignition temperature of MgB2 is greatly reduced after alloying. The ignition reaction of MgB2 mainly occurs on the surface and the ignition process has two stages. In the initial stage of ignition, the large flame morphology and combustion state are close to the combustion with gaseous Mg, whereas the subsequent combustion process is close to the combustion process of B. Compared with boron, the ignition temperature of MgB2 is greatly reduced which suggests that MgB2 may be used in gunpowder, propellant, explosives, and pyrotechnics due to its improved ignition performance.

Infrared Sensor ZTP-135SR and Its Application in Infrared Body Temperature Measurement

Body temperature is an essential physiological parameter. Conducting non-contact, fast and accurate measurement of temperature is increasing important under the background of COVID-19. The study introduces an infrared temperature measurement system based on the thermopile infrared temperature sensor ZTP-135SR. Extracting original temperature date of sensor, post-amplification and filter processing have been performed to ensure accuracy of the system. In addition, the temperature data of environmental compensation which obtained by polynomial fitting is added to the system to further improve measurement accuracy.

A novel framework on intelligent detection for module defects of PV plant combining the visible and infrared images

Solar Photovoltaic (PV) industry has achieved rapid development in recent years. However, it is difficult and costly to detect the micro fault area in a large PV power plant due to environmental factors and missing data. Most faults can be detected by the infrared temperature measurement method, but the infrared camera characteristics constrain it. This paper proposed a novel framework, consisting of image acquirement, image segmentation, fault orientation and defect warning, to remedy the limitations for PV module defects. The visible and infrared PV array images are taken under the same conditions by a dual infrared camera at low altitudes. The deep learning methods, including the fifth version of You Only Look Once (YOLOv5) algorithm and Deep Residual Network (ResNet) algorithm, are introduced to this framework. Hence, this framework has strong capability to suit almost all brightness conditions, by the combination of image segmentation from visible images and fault location on infrared images. The results show that this framework dramatically improves the separation speed of photovoltaic array to 36 Fps and the accuracy of fault detection to 95% by infrared image marked with the segmented area.

Research on Signal to Noise Ratio Characteristic Influence About Temperature Noise to Infrared Compound Eye Lens Array Imaging

In order to study the effect of temperature noise on the performance of infrared compound eye lens array imaging system, and based on black body infrared radiation and infrared temperature measurement theory, this paper studied the effects of black body radiation temperature and ambient temperature changing on the imaging performance about signal to noise ratio (SNR) and definition of infrared compound eye lens imaging system. Theoretical mathematical model about influence of temperature noise on infrared compound eye imaging system was built. After finishing numerical simulation analysis and experimental test verification, not only the correctness of the model was proved, but also the conclusion was obtained that the clearer the image of the target presented by the compound eye lens array system, that was, the greater the value of SNR was, under the condition of the lower the ambient temperature noise was relative to the black body radiation temperature noise. Meanwhile, the phenomenon that limited SNR of the imaging capability of infrared compound eye lens array imaging system was about 26.4 db was found in the experiment. A theoretical basis for further research was provided, which was the control method of how to reduce the influence of temperature noise on infrared compound eye lens imaging system and to improve SNR of the system.

Infrared temperature measurements and DEM simulations of heat transfer in a bladed mixer

AbstractAn understanding of heat transfer in a bladed mixer is important for drying of pharmaceutical drug crystals. This study presents thermal imaging experiments of the particle bed surface in a bladed mixer to investigate how the impeller speed influences the rate and the uniformity of heat transfer. Next, the process is simulated using the discrete element method. The bed thermal properties are lumped into an effective thermal conductivity, that is calibrated for one impeller speed. The experiments and the simulations show the same trends and generally agree well for all agitated beds. However, to obtain good agreement of the rate of heat transfer between the simulations and experiments in a static bed, we need to adopt a higher thermal conductivity than for the agitated beds. Finally, we discuss the implications of these results for the design of operating protocols.

Effects of the distance and test angle on the precision of infrared temperature measurement

The target distance and test angle are the main factors that affect the accuracy of infrared temperature measurement. To study the infrared temperature measurement precision of different heat source intensities at different distances and test angles, a temperature measurement test with built-in heat source within the rod of the insulator was designed. By setting four different heat source temperatures on the heating film, the temperature data were collected by infrared camera at the distances of 3, 6, 9, 12 m and 15 m and three test angles of 0 °, 90° and 180°, respectively, and the variation law of the measurement results was analysed. The main conclusions are as follows. As the distance increases, the measured values basically show a downward trend. When the distance reaches 12 m, the temperature fluctuates significantly. When the angle between the observation direction and the heat source is 0 °, the measurement value is the highest, followed by the 90° direction, and the lowest is the 180° direction, which indicates that the test angle has an obvious influence on the measurement results. With the increase of heat source temperature, the infrared temperature measurement value increases gradually and tends to be saturated. When an infrared device is adopted to measure the temperature of the insulators in service, it is necessary to pay attention to the influence of the distance and angle on the value in engineering practice.

Study on influencing factors and laws of infrared temperature measurement of silicone rubber composite insulator

Silicon rubber composite insulator is favoured by power system because of its excellent anti-pollution flashover performance. Among them, the core rod is an important structural component to bear the mechanical load of composite insulator. In recent years, there have been many brittle fracture faults of composite insulators in China, which directly affect the reliability of transmission lines. The composite insulator is usually accompanied by abnormal heating during the aging process. As an effective live detection method, infrared temperature measurement can find the defects of composite insulator in time and reduce the occurrence of string breaking accidents. In this paper, by artificially simulating the abnormal temperature rise of composite insulator, infrared temperature measurement was carried out under the conditions of different observation distance, different observation angle, different sheath thickness and different heat source temperature, so as to explore the influencing factors and laws of infrared temperature measurement of composite insulator. The results show that due to the difference of heat loss, sheath barrier and radiation ratio in thermal radiation propagation, the measured temperature decreases and the absolute temperature difference increases with the increase of observation distance, sheath thickness and observation angle. The built-in heat source temperature increases the total internal heat, which can partially weaken the influence of sheath thickness on the measured temperature and significantly expand the difference caused by observation angle.

Influence of sheath thickness and core rod diameter on fault temperature rise of composite insulator

Infrared temperature measurement is an effective means for insulator health monitoring, and the theoretical basis and the subsequent diagnosis methods have been widely studied. However, in practical applications, the influence of insulator itself on fault temperature rise is rarely considered. In this paper, the temperature rise experiment of composite insulator was conducted to study the influence of sheath thickness and core rod diameter on fault temperature rise. According to the experimental results, the evolution law of fault temperature rise with the change of sheath thickness and core rod diameter was obtained. On this basis, the design strategy for composite insulators was proposed.

Research on Calibration Method of Infrared Temperature Measurement System Near Room Temperature Field

The calibration accuracy of the infrared temperature measurement system near room temperature field is easily affected by the calibration environment. In this paper, an equivalent blackbody calibration method is proposed for this problem. In this method, the target radiation and ambient radiation superimposed in calibration data are separated by two calibration functions at different ambient temperatures, and an equivalent blackbody calibration function is constructed. The experimental verification of the proposed method is carried out, and the results show that the proposed method has a better calibration effect for the surface blackbody than the commonly used environmental compensation methods. This method can effectively improve the calibration accuracy of infrared temperature measurement system near room temperature field, and further improve the infrared temperature measurement theory.

Polymorphic Temperature Measurement Method of Molten Iron After Skimmer in Ironmaking Process

In the ironmaking process, online and accurate temperature measurement of molten iron after the skimmer is an important problem that the steel industry is eager to solve. However, the different dust interference and the oxide layer covered on the molten iron flow make this problem not easy. To solve this problem, this article proposed a polymorphic temperature measurement method of molten iron after the skimmer. First, an infrared temperature measurement system is designed to capture the thermal images of molten iron flow after the skimmer. Second, considering that the dust has different interference states, the idea of polymorphism is introduced, and the interference states of dust are identified. Then, a polymorphic measurement model of the oxide layer is established to accurately measure the oxide layer temperature under different dust interference states. Finally, a polymorphic temperature measurement model of the molten iron after the skimmer is derived based on the heat transfer between the molten iron and the oxide layer. Industrial experiment results indicate that the proposed polymorphic temperature measurement method can accurately measure the temperature of molten iron after the skimmer and provide reliable molten iron temperature (MIT) data for blast furnace (BF) operators.