Infrared thermography for prediction of spontaneous combustion of sulfide ores

The method of infrared thermography to predict the temperature of the sulfide ores has a large error. To solve this problem, the temperature of the sulfide ores is measured by thermal infrared imager and recording thermometric instrument contrastively. The main factors, including emissivity, distance, angle and dust concentration that affect the temperature measurement precision, are analyzed. The regression equations about the individual factors and comprehensive factors are obtained by analyzing test data. The application of the regression equations improves the precision of the thermal infrared imager. The geometric information lost in traditional infrared thermometry is determined by visualization grid method and interpolation method, the relationship between the infrared imager and geometry information is established. The geometry location can be measured exactly.

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint based on infrared thermography

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint undergoing cyclic loading was investigated by infrared thermography. Temperature evolution throughout a fatigue process was presented and the mechanism of heat generationwas discussed. Fatigue limit of the welded joint was predicted and the fatigue damage was also assessed based ontheevolution of the temperatureand hotspot zone on the specimen surfaceduring fatigue tests. The presented results show that infrared thermography can not onlyquicklypredict the fatigue behavior of the welded joint, but also qualitatively identify the evolution of fatigue damage in real time. It is found that the predicted fatigue limit agrees well with the conventionalS-Nexperimental results. The evolution of the temperatureand hotspot zone on the specimen surface can be an effectivefatigue damage indicatorfor effectiveevaluationof magnesium alloy electron beam welded joint.

Anisotropy of Fatigue Behavior and Tensile Behavior of 5A06 Aluminum Alloy Based on Infrared Thermography

The fatigue behavior during high cycle fatigue testing and the tensile behavior of 5A06 aluminum alloy considering the anisotropy were studied.Two types of specimens including longitudinal specimen（parallel to the rolling direction） and transverse specimen（perpendicular to the rolling direction） were prepared.Infrared thermography was employed to monitor the temperature evolution during the fatigue and tensile tests.The temperature evolution curves in the two directions were contrastively analyzed.It is found that the temperature evolution during fatigue process possesses four stages：initial temperature rise stage,slow temperature decline stage,rapid temperature rise stage,and finial temperature decline stage.The heat generating mechanisms of the four stages are discussed.Obvious differences can be found between the longitudinal specimen and transverse specimen in fatigue strength and fatigue life.The fatigue strength and fatigue life of longitudinal specimen are higher than those of transverse specimen.During the tensile and fatigue testing process,the fracture temperature in the transverse direction are higher than that in the longitudinal direction.The fatigue strength prediction by means of infrared thermography has a good consistency with that by the traditional method.

Bridge Girder Crack Assessment Using Faster RCNN Inception V2 and Infrared Thermography

Manual inspections of infrastructures such as highway bridge, pavement, dam, and multistoried garage ceiling are time consuming, sometimes can be life threatening, and costly. An automated computerized system can reduce time, faulty inspection, and cost of inspection. In this study, we developed a computer model using deep learning Convolution Neural Network (CNN), which can be used to automatically detect the crack and non-crack type structure. The goal of this research is to allow application of state-of-the-art deep neural network and Unmanned Aerial Vehicle (UAV) technologies for highway bridge girder inspection. As a pilot study of implementing deep learning in Bridge Girder, we study the recognition, length, and location of crack in the structure of the UTC campus old garage concrete ceiling slab. A total of 2086 images of crack and non-crack were taken from UTC Old Library parking garage ceiling using handheld mobile phone and drone. After training the model shows 98% accuracy with crack and non-crack types of structures.

Quantification by Signal to Noise Ratio of Active Infrared Thermography Data Processing Techniques

In this paper, the use of a signal to noise ratio (SNR) is proposed for the quantification of the goodness of some selected processing techniques of thermographic images, such as differentiated absolute contrast, skewness and kurtosis based algorithms, pulsed phase transform, principal component analysis and thermographic signal reconstruction. A new hybrid technique is also applied (PhAC—Phase absolute contrast), it combines three different processing techniques: phase absolute contrast, pulsed phase thermography and thermographic signal reconstruction. The quality of the results is established on the basis of the values of the parameter SNR, assessed for the present defects in the analyzed specimen, which enabled to quantify and compare their identification and the quality of the results of the employed technique.

Effect of preload force on heat generation of fatigue crack in ultrasonic infrared thermography

The heat generation behaviors of fatigue crack are deeply investigated under different preload forces combing numerical simulation and experiment.Firstly,a multi-contact simulation model is applied to stimulate the crack surfaces contact and the horn-sample contact under ultrasonic excitation for calculating the temperature fields.Then,the ultrasonic infrared thermography testing and the microscope testing are carried out for the heat generation and the plastic deformation behaviors of crack region under different preload forces.On this basis,an indirect observation method based on dots distribution is proposed to estimate the plastic deformation on crack contact surfaces.The obtained results show that the temperature rise of crack region increases with the increase of preload force when the preload force is less than 250 N,while the temperature rise rapidly declines due to the plastic deformation on crack contact surfaces and the inhibition effect when the preload force is 280 N.Moreover,the plastic deformation does not lead to the crack propagation,but reduces the detection repeatability of fatigue crack.This work provides an effective method for optimizing testing conditions in practical testing processes,which will be helpful to the establishment of testing standards for batches of test objects in ultrasonic infrared thermography testing.

Comparison between Microwave Infrared Thermography and CO₂Laser Infrared Thermography in Defect Detection in Applications with CFRP

This paper presents two infrared thermography methods with CO2 Laser excitation and microwave excitation applied to defect detection in CFRP. The tests were conducted with two specimens, one with defect, and another one without defect. On two concrete plates 40 cm× 40 cm× 4.5 cmwere reinforced by CFRP;the defects were made by the absence of adhesive on an area10 cm× 10 cm. The specimens were heated by microwave, generated by a commercial magnetron of 2.45 GHz and guided by a pyramidal horn antenna, with a power of 360 W within 150 s. Another series of the tests was conducted with CO2 Laser, wavelength 10.6 μm, by heating the samples with a power of 300 W within 40 s. An infrared camera sensitive to medium waves in range of 3 - 5 μm, with a detector of 320 × 256 matrix detector in InSb (Indium Antimonide), was used to record the thermograms. As a result, the CO2 Laser excitation is better for the delamination detection in CFRP. This study opens interesting perspectives for inspecting other types of defects in materials sciences;the microwave excitation is suitable for the deep defects in the materials whereas the CO2 Laser excitation is better for the defects near the surface of the materials.

Counting Method of Mangrove Pests Based on Infrared Thermography

In the field of plant protection,certain methods for assessing the current pest situation and implementing appropriate protection countermeasures can effectively protect plants while saving manpower and material resources.However,current pest monitoring methods are primarily based on the stage of"seeing,hand checking,disc shooting and net catching",and the level of automation is low.Manual methods are time-consuming,prone to error,and difficult to review.We designed a method based on infrared thermography principle for counting Ricania guttata(Walker),a pest which is harmful to mangrove plants.This method,which is based on thermal infrared images and binarized image segmentation,realizes image processing of surface temperature,effectively distinguishes pests and sticky board,automatically counts the number of pests,and expands the data source based on image processing.Furthermore,this method contributes to the solution of the problem that counting error of insect close to the color of sticky board is greater in image recognition of visible light,when the pest color is close to the stick board.It can facilitate manual investigation of mangrove pests,simply and efficiently count the number of pests on the stick board,and provide data and technical support for pest condition analysis and control.

Pulse modulated microwave and infrared thermography for superficial hyperthermia

A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 ℃ in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 （denoted by scenarios 1-4）. Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise （MTR） is 6.6 and 8 ℃ in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.

Study on divertor heat flux under n=3 and n=4 resonant magnetic perturbations using infrared thermography diagnostic in EAST

Resonant magnetic perturbations(RMPs)with high toroidal mode number n are considered for controlling edge-localized modes(ELMs)and divertor heat flux in future ITER H-mode operations.In this paper,characteristics of divertor heat flux under high-nRMPs(n=3 and 4)in H-mode plasma are investigated using newly upgraded infrared thermography diagnostic in EAST.Additional splitting strike point(SSP)accompanying with ELM suppression is observed under both RMPs with n=3 and n=4,the SSP in heat flux profile agrees qualitatively with the modeled magnetic footprint.Although RMPs suppress ELMs,they increase the stationary heat flux during ELM suppression.The dependence of heat flux on q_(95)during ELM suppression is preliminarily investigated,and further splitting in the original strike point is observed at q 495=during ELM suppression.In terms of ELM pulses,the presence of RMPs shows little influence on transient heat flux distribution.

Infrared thermography in metabolic diseases

The prevalence of metabolic diseases,some diseases that are seriously harmful for human health and affect the quality of life,is increasing year by year.Early detection and intervention is the common strategy to deal with them.Infrared thermography(IRT)is a special medical imaging technology which can capture the changes of skin temperature associated with metabolic disorders.It might be a new method for early detection of metabolic diseases.The purpose of this review is to summarize advances of the use of IRT in evaluating single metabolic disorder such as obesity,hyperglycemia and hypertension,complex metabolic disorders such as metabolic syndrome and target organ damage such as coronary artery atherosclerosis and diabetic foot.The characteristic of thermograms of metabolic disease patients,the changes of thermal maps during the development of the disease,and the lacks in current studies are also discussed in the article.

Laser Heating and Infrared Thermography of Building Materials

In this work, a 532 nm diode CW laser is used to heat samples used as building materials at a 1 meter standoff distance while using an FLIR (Forward-Looking Infrared) thermal camera to monitor and record the heating and then cooling of each sample after lasers are switched off. The data is then analyzed using FLIR proprietary software. Since the absorption spectra of materials are unique, using multiple lasers of different wavelengths to simultaneously shine onto the sample at different locations would give enough thermal data to successfully characterize the samples within a reasonable amount of time. The results are very promising for applications involving non-destructive detection and classification of materials.

基于红外热成像技术的隧道隐性渗漏检测研究

因隧道安装防火板,导致渗漏水隐蔽在防火板背后而不易被检测。红外热成像技术是一种非接触无损检测技术,因其对表面热辐射敏感而常用来测量表面温度场。基于红外热成像技术,研究了隧道隐性渗漏车载非接触式快速检测的可行性。结合某长江隧道,将红外热成像设备安置在车顶,对隧道内表面实施移动扫描拍照,并通过红外热力图准确识别既有渗漏点。为了进一步验证检测效果,人为在防火板表面涂湿模拟渗漏,该渗漏过程可以被准确识别。通过试验研究,表明红外热成像技术用于隧道隐性渗漏车载非接触式快速检测是可行性的。

NDI of Rail Squats and Estimating Defect Size and Location Using Lock-In Thermography

Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence and measure their depths. This technique needs to be direct contact between the probe and the rail head, with a coupling fluid in at the interface. Other weaknesses of these ultrasonic techniques include false detections as well as missed detections. Infrared thermography is a relatively new non-destructive inspection technique used for a wide range of applications but is not used for rail squat detection. Lock-in thermography is a non-destructive inspection technique that can be used for the detection of near surface defects. It utilizes an infrared camera to detect the thermal waves and then produces a thermal image, which displays the local thermal wave variation in phase or amplitude. In inhomogeneous materials, the amplitude and phase of the thermal wave carries information related to both the local thermal properties and the nature of the structure being inspected. This comparison is then used to determine the phase angle difference (Δf) between the input and the thermal response of the object. The aim of this paper is to determine whether lock-in thermography can be used to firstly locate squats in rails, and secondly measure their depths. It has demonstrated the feasibility for using such a technique in generating thermal responses that could be adequately utilized for the purpose of defect characterization.

基于IRt/c.3X的红外地表温度传感器设计

基于自动气象站中考核地表温度所使用的IRt/c.3X红外传感器,设计一个以MSP430F2013为核心的数字式红外温度传感器。通过高精度基准电压源AD780实现对前端模拟式传感器内部K型热电偶的冷端补偿;利用单片机片上的可编程增益放大器PGA和16位模数转换器SD16_A完成热电偶输出信号的数字化;并采用分段线性拟合方法使系统的测温平均误差在±0.1℃以内,温度分辨率在常温范围内达到0.012 7℃。设计出的数字式红外地表温度传感器具有高精度、高分辨率、低功耗等特点。

An overview of the thermography-based experimental studies on roadway excavation in stratified rock masses at CUMTB

This paper presents an overview of experimental investigations conducted at China University of Mining and Technology Beijing(CUMTB) on roadway excavation using large-scale geomechanical model tests.The simulated sedimentary rocks are composed by alternating layers of sandstone, mudstone and coal seam inclined at varied angles with respect to the horizontal including 0°, 45°, 60°, and 90°. During the excavation, infrared thermography was employed to detect the thermal response of the surrounding rocks under excavation. The obtained raw thermograms were processed using denoising algorithm, data reduction procedure and Fourier analysis. The infrared temperature(IRT) characterizes the overall rock response; the processed thermal images represent the structural behavior, and the Fourier spectrum describes damage development in the frequency domain. Deeper understanding was achieved by the comparative analyses of excavation in differently inclined rock masses using the image features of IRTs, thermal images and Fourier spectra.

Remote sensing of bark beetle damage in Norway spruce individual tree canopies using thermal infrared and airborne laser scanning data fusion

Background:Increasing threat to Central Europe’s forests from the growing population of the European spruce bark beetle Ips typographus (L.) calls for developing highly effective methods of detection of the infestation spots. The main goal of this study was to establish an automatic workflow for detection of dead trees and trees in poor condition of Picea abies using Middle Wave Infrared spectral range obtained from the aircraft.Methods:The studies were conducted in Wigry National Park (Poland) in 2020. A fusion of aircraft thermal data and laser scanning was used. Synchronous with thermal data acquisition ground reference data were obtained for P. abies in different health conditions. Determination of the range of canopy temperatures characteristic of the three condition states (‘healthy’,‘poor condition’,‘dead’) was performed using K-mean clustering. The accuracy of the method was evaluated on two validation sets:(1) individual tree canopies determined by photointerpretation, and (2) automatic segmentation of laser scanning data.Results:The results showed that the average temperature of ‘healthy’trees was 27.70℃, trees in ‘poor condition’28.57℃, and ‘dead’trees 30.17℃. High temperature differences between ‘healthy’and ‘dead’P. abies made it possible to distinguish these two condition classes with high accuracy. Lower accuracies were obtained for the class of ‘poor condition’, which was found to be confusing with both ‘healthy’and ‘dead’trees. According to results from the first validation set, a high overall accuracy of 0.60 was obtained. For the second validation set, the overall accuracy was reduced by 11%.Conclusions:This study indicates that canopy temperature recorded from the airborne level is a variable that differentiates ‘healthy’spruces from those in ‘poor condition’and the ‘dead’trees. The results confirmed that thermal and airborne laser scanning data fusion allows for creating a quick and simple workflow, which can successfully separate individual tree canopies and identify P. abies attacked by I. typographus. Further research is needed to identify trees in the early stages of invasion.

红外热成像精准电参数刺激治疗早发型卵巢功能不全的临床研究

目的:探讨采用红外热成像精准电参数刺激治疗早发型卵巢功能不全的临床效果。方法:选取100例早发性卵巢功能不全患者作为研究对象,按照不同治疗方法分为对照组与研究组,每组各50例。对照组采用雌孕激素进行治疗;研究组采用红外热成像精准电参数刺激治疗。比较治疗前及治疗后1、2、3个月两组患者血清激素[促卵泡生成素(FSH)、促黄体生成素(LH)、雌二醇(E2)及抗苗勒氏管激素(AMH)]水平、血流情况[卵巢血管收缩期峰值血流速度(PSV)、计算搏动指数(PI)及阻力指数(RI)]、基础窦卵泡数及卵巢体积,并比较两组患者不良反应发生情况及临床疗效。结果:治疗1、2、3个月后,两组患者FSH及LH水平均下降,且研究组低于对照组;E2及AMH水平均升高,且研究组高于对照组(P<0.05)。治疗3个月后,两组患者PSV水平均升高,PI水平均降低,且研究组RI水平低于治疗前(P<0.05)。治疗2、3个月后,两组患者基础窦卵泡数及两侧卵巢体积水平均呈上升趋势;治疗3个月后,研究组基础窦卵泡数及两侧卵巢体积水平均高于对照组(P<0.05),治疗有效率高于对照组(P<0.05),不良反应发生率低于对照组(P<0.05)。结论:采用红外热成像精准电参数刺激治疗早发性卵巢功能不全的患者安全性较高,利于改善患者性激素水平,并可增加基础窦卵泡数及增大卵巢体积,具有较好的临床疗效,可以在基层医院临床推广应用。

低空监控系统的红外小目标检测方法

无人机遥感系统在检测复杂背景下红外小目标时存在虚警过高的问题,结合卷积神经网络提出一种两阶段的无人机遥感系统红外小目标检测模型。第一阶段利用Unet神经网络学习红外图像中目标的深度语义特征与浅层位置特征,同时增强红外小目标信号,并抑制背景信号。第二阶段利用Faster R-CNN对第一阶段输出的图像进行分析,检测图中红外小目标的位置与边框。在公开的无人机遥感系统红外小目标检测数据集上完成了验证实验,结果表明该模型将三个复杂背景数据集下红外小目标的检测精度分别提高了13.2、9.8与13个百分点,每秒处理的帧数分别增加了11、14与13。

基于匹配法的不同种类煤和矸石发射率测量研究

煤和矸石的种类、表面纹理结构、变质和发育程度等因素都会对其发射率产生较为显著的影响,精准的发射率参数设置对红外热像仪测温及煤和矸石红外图像的识别至关重要。提出了一种基于匹配法的煤和矸石发射率测量方法,即采用表面热电偶与红外热像仪相结合的方式测量煤和矸石发射率。用密闭的电热炉对被测煤和矸石进行均匀加热,待被测煤和矸石均匀受热且稳定后,用表面热电偶对被测煤和矸石的选定区域进行真实温度测定(标定为t1),然后用红外热像仪对同一区域进行温度测定(标定为t2),最后对红外热像仪的发射率进行调试,当t2=t1时,得出的发射率即为被测煤和矸石在该温度下的真实发射率。实验结果表明:(1)等温条件下,煤和矸石表面越粗糙,其发射率数值越大,表明煤和矸石表面的粗糙度是导致二者产生不同发射率的内在因素。(2)4种不同种类煤和矸石发射率随温度的增大呈幂函数降低,且拟合函数相关系数R2达0.98以上,验证了匹配法应用于煤和矸石发射率测量的可行性。(3)采用反代法得出在不同温度条件下实测值与理论值的误差率均小于3%,验证了实验中测量的煤和矸石发射率的准确性。