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 an...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.展开更多
Musculoskeletal injuries are among the most common causes of disability worldwide,with early detection and appropriate intervention critical to minimizing long-term complications.Infrared thermography(IRT)has emerged ...Musculoskeletal injuries are among the most common causes of disability worldwide,with early detection and appropriate intervention critical to minimizing long-term complications.Infrared thermography(IRT)has emerged as a noninvasive,real-time imaging modality that captures superficial temperature changes reflecting underlying physiological processes such as inflammation and vascular alterations.This review explores the fundamental principles of medical thermography,differentiates between passive and active approaches,and outlines key technological advancements including artificial intelligence integration.The clinical utility of IRT is discussed in various contexts–ranging from acute soft tissue injuries and overuse syndromes to chronic pain and rehabilitation monitoring.Comparative insights with conventional imaging techniques such as ultrasound and magnetic resonance imaging are also presented.While IRT offers functional imaging capabilities with advantages in portability,safety,and speed,its limitations–such as lack of deep-tissue penetration and protocol standardization–remain significant barriers to broader adoption.Future directions include the integration of IRT with other imaging modalities and digital health platforms to enhance musculoskeletal assessment and injury prevention strategies.展开更多
The airborne diffusion of saliva droplets during respiratory activities is one of the major factors in the spread of infections.During the COVID-19 pandemic,the use of protective face masks was essential to reduce the...The airborne diffusion of saliva droplets during respiratory activities is one of the major factors in the spread of infections.During the COVID-19 pandemic,the use of protective face masks was essential to reduce the risk of infection and spread of SARS-CoV-2.The face mask is able to significantly reduce the saliva droplet emission in front of the person.However,the use of masks also produces a particle leakage towards the back of the person,which could increase the infection risk of people behind the subject.Most of the experimental investigations applied invasive and/or complex experimental techniques to evaluate the face masks leakage.The primary objective of this study is to develop a novel,non-invasive methodology for assessing rearward droplet emission associated with the use of protective face masks.Specifically,a thermographic analysis of the thermal footprint released during ordinary and extraordinary respiratory activities is presented,evaluating the maximum temperature,the detection time,and the spread area of the thermal footprint.Both surgical and FFP2 face masks were tested.Two different subjects were involved in the experimentation to evaluate the influence of face conformation.The findings indicate that the area influenced by droplet dispersion is larger when wearing a surgical mask compared to an FFP2 mask,with the highest recorded temperatures observed for the surgical mask.The thermal footprint was found to be strongly dependent on individual facial morphology and mask fit.Notably,the FFP2 mask also altered the position of the thermal footprint,which was primarily confined to the region near the neck.展开更多
The motivation of this paper is to explore the application of Step-Heating Thermography(SHT)as a technique capable of inspecting new composite rail carbodies using demanding requirements set by the rail manufacturing ...The motivation of this paper is to explore the application of Step-Heating Thermography(SHT)as a technique capable of inspecting new composite rail carbodies using demanding requirements set by the rail manufacturing industry.A large composite sample,with Polytetrafluoroethylene(PTFE)artificial defects,replicating a side-wall section of a new rail carbody,was manufactured and inspected for surface and subsurface defects in this research.The sample,characterized by its large thickness,consists of a monolithic Carbon Fibre Reinforced Polymers(CFRP)component(20mm thickness)and a CFRP-PET foam-CFRP sandwich(40mm total thickness)component fused together.The main challenge of the inspection procedure was to apply reflection mode thermography and detect defects in the entire thickness of the sample that exhibits both low emissivity and thermal insulating properties,especially at the sandwich sections of the sample.The paper explored thermography procedures that would be able to detect large numbers of defects under one single acquisition and would be applied under an automated inspection process leading to the detection of defects only up to 5mm in the CFRP sections of the sample while no defects were able to be detected at the back skin of the sample.展开更多
Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operationa...Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operational costs and poses significant risks to public safety.Effective maintenance,repair,and rehabilitation strategies are needed to ensure civil infrastructure’s overall safety and reliability.Non-Destructive Evaluation(NDE)methods are utilized to assess latent damage and provide decision-makers with real-time information for mitigating hazards.Within the last decade,there has been a significant increase in the research and development of innovative NDE techniques to improve data processing and promote efficient and accurate infrastructure assessment.This paper aims to review one of those methods,namely,Infrared Thermography(IRT),and its applications in civil infrastructure.A comprehensive review is presented by investigating numerous journal articles,research papers,and technical reports describing numerous IRT applications for bridges,buildings,and general civil structures made from different materials.The capability of IRT to identify and pinpoint anomalies,typically in the early stages of degradation,has excellent potential to improve the safety and shore up the dependability of civil infrastructures while reducing expenses tied to maintenance and rehabilitation.Furthermore,the non-invasive nature of IRT is beneficial in mitigating disturbances and downtime that may occur during various inspection procedures.It is highlighted that IRT is a highly versatile and effective tool for infrastructure condition assessment.With further advancement and fine-tuning of the available techniques,it is likely that IRT will continue to gain significant popularity in maintaining and monitoring civil infrastructure.展开更多
Vortex-induced vibration of hydrofoils is concerned with structural safety and noise level in hydraulic machinery and marine engineering.The research on vibration characteristics under different operating conditions i...Vortex-induced vibration of hydrofoils is concerned with structural safety and noise level in hydraulic machinery and marine engineering.The research on vibration characteristics under different operating conditions is significant.In this study,numerical simulations are conducted to investigate the vortex-induced vibration responses of an elastically suspended hydrofoil with blunt trailing edge in pitch direction.The work studies the effects of four parameters,namely the structural natural frequency,mass ratio,initial attack angle,and Reynolds number on vibration characteristics,with special emphasis on frequency lock-in.Results indicate that as the structural natural frequency changes,the vibration amplitude may increase substantially within a certain frequency range,in which the vortex shedding frequency locks into the structural natural frequency,and frequency lock-in occurs.In addition,with increasing the mass ratio,the frequency range of lock-in becomes narrower,and both the upper and lower thresholds decrease.As the initial attack angle increases from 0◦to 6◦,the lock-in range gets reduced.Over the three Reynolds numbers(6×10^(5),9×10^(5),and 12×10^(5)),the lock-in range remains virtually unchanged.Moreover,for a certain structural natural frequency,modifying the mass ratio,initial attack angle,and Reynolds number could effectively suppress the vibration amplitude.展开更多
Objective:To evaluate the use of infrared thermography technology for objective and quantitative syndrome differentiation and treatment in traditional Chinese medicine(TCM),specifically in patients with Chaihu Guizhi ...Objective:To evaluate the use of infrared thermography technology for objective and quantitative syndrome differentiation and treatment in traditional Chinese medicine(TCM),specifically in patients with Chaihu Guizhi Ganjiang Decoction syndrome.Methods:Data were collected from over 100 patients diagnosed with Chaihu Guizhi Ganjiang Decoction syndrome at Professor Li Leyu’s endocrinology clinic,Zhongshan Hospital of Traditional Chinese Medicine,Guangdong Province,between April 2021 and April 2022.Body surface temperature data were obtained using the MTI-EXPRO-2013-B infrared thermography system.Principal component analysis(PCA)was applied to differentiate temperature distribution characteristics between genders,and a neural network prediction model was constructed for syndrome diagnosis.Results:Infrared thermography effectively captured surface temperature characteristics of patients with Chaihu Guizhi Ganjiang Decoction syndrome.PCA identified one principal component with a variance explanation rate of 73.953%for females and two principal components with a cumulative variance explanation rate of 77.627%for males.The neural network model demonstrated high predictive performance,with an area under the ROC curve of 0.9743 for the training set and 0.9889 for the validation set.Sensitivity was 1,specificity 0.8636,precision 0.8846,accuracy 0.9333,and the F1 score 0.9388.Conclusion:Infrared thermography provides an innovative,objective,and quantitative method for syndrome differentiation and treatment in TCM.It represents a significant advancement in transitioning from traditional empirical approaches to modern,visualized,and precise diagnosis and treatment.This study underscores the potential of integrating advanced technologies in TCM for enhanced clinical application and modernization.展开更多
高速铁路轮轨系统在服役过程中产生的疲劳裂纹是威胁行车安全的重大隐患。传统的无损检测方法难以有效识别处于闭合或半闭合状态的早期微小裂纹,尤其是在列车运行载荷作用下的动态工况。针对这一挑战,本文提出并系统研究了一种基于涡流...高速铁路轮轨系统在服役过程中产生的疲劳裂纹是威胁行车安全的重大隐患。传统的无损检测方法难以有效识别处于闭合或半闭合状态的早期微小裂纹,尤其是在列车运行载荷作用下的动态工况。针对这一挑战,本文提出并系统研究了一种基于涡流脉冲热成像(Eddy Current Pulsed Thermography,ECPT)技术的轮轨疲劳裂纹检测方法。研究首先构建了负载作用下的非稳态疲劳裂纹多物理场模型,通过有限元仿真与实验相结合,深入探究了局部接触(闭合)裂纹的涡流-热响应机理,并揭示了裂纹闭合深度与表面温度场特征(如等温线内凹现象)之间的定量关系。在此基础上,自主研制了适用于车轮与钢轨的动态ECPT检测平台及专用磁轭传感器,并开展了高铁轮轨实物的动态检测试验。结果表明,所提方法不仅能有效区分开口与闭合裂纹,还能对不同深度、不同尺寸的疲劳裂纹进行可靠检出,检出深度范围可达0.35mm至5mm。结合主成分分析(PCA)与张量分解等图像增强算法,显著提升了缺陷的信噪比与可视化效果,为高铁轮轨疲劳裂纹的在线、高效、精准检测提供了重要的理论依据与技术支撑。展开更多
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 mechan...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.展开更多
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 the...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.展开更多
文摘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.
文摘Musculoskeletal injuries are among the most common causes of disability worldwide,with early detection and appropriate intervention critical to minimizing long-term complications.Infrared thermography(IRT)has emerged as a noninvasive,real-time imaging modality that captures superficial temperature changes reflecting underlying physiological processes such as inflammation and vascular alterations.This review explores the fundamental principles of medical thermography,differentiates between passive and active approaches,and outlines key technological advancements including artificial intelligence integration.The clinical utility of IRT is discussed in various contexts–ranging from acute soft tissue injuries and overuse syndromes to chronic pain and rehabilitation monitoring.Comparative insights with conventional imaging techniques such as ultrasound and magnetic resonance imaging are also presented.While IRT offers functional imaging capabilities with advantages in portability,safety,and speed,its limitations–such as lack of deep-tissue penetration and protocol standardization–remain significant barriers to broader adoption.Future directions include the integration of IRT with other imaging modalities and digital health platforms to enhance musculoskeletal assessment and injury prevention strategies.
文摘The airborne diffusion of saliva droplets during respiratory activities is one of the major factors in the spread of infections.During the COVID-19 pandemic,the use of protective face masks was essential to reduce the risk of infection and spread of SARS-CoV-2.The face mask is able to significantly reduce the saliva droplet emission in front of the person.However,the use of masks also produces a particle leakage towards the back of the person,which could increase the infection risk of people behind the subject.Most of the experimental investigations applied invasive and/or complex experimental techniques to evaluate the face masks leakage.The primary objective of this study is to develop a novel,non-invasive methodology for assessing rearward droplet emission associated with the use of protective face masks.Specifically,a thermographic analysis of the thermal footprint released during ordinary and extraordinary respiratory activities is presented,evaluating the maximum temperature,the detection time,and the spread area of the thermal footprint.Both surgical and FFP2 face masks were tested.Two different subjects were involved in the experimentation to evaluate the influence of face conformation.The findings indicate that the area influenced by droplet dispersion is larger when wearing a surgical mask compared to an FFP2 mask,with the highest recorded temperatures observed for the surgical mask.The thermal footprint was found to be strongly dependent on individual facial morphology and mask fit.Notably,the FFP2 mask also altered the position of the thermal footprint,which was primarily confined to the region near the neck.
文摘The motivation of this paper is to explore the application of Step-Heating Thermography(SHT)as a technique capable of inspecting new composite rail carbodies using demanding requirements set by the rail manufacturing industry.A large composite sample,with Polytetrafluoroethylene(PTFE)artificial defects,replicating a side-wall section of a new rail carbody,was manufactured and inspected for surface and subsurface defects in this research.The sample,characterized by its large thickness,consists of a monolithic Carbon Fibre Reinforced Polymers(CFRP)component(20mm thickness)and a CFRP-PET foam-CFRP sandwich(40mm total thickness)component fused together.The main challenge of the inspection procedure was to apply reflection mode thermography and detect defects in the entire thickness of the sample that exhibits both low emissivity and thermal insulating properties,especially at the sandwich sections of the sample.The paper explored thermography procedures that would be able to detect large numbers of defects under one single acquisition and would be applied under an automated inspection process leading to the detection of defects only up to 5mm in the CFRP sections of the sample while no defects were able to be detected at the back skin of the sample.
文摘Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operational costs and poses significant risks to public safety.Effective maintenance,repair,and rehabilitation strategies are needed to ensure civil infrastructure’s overall safety and reliability.Non-Destructive Evaluation(NDE)methods are utilized to assess latent damage and provide decision-makers with real-time information for mitigating hazards.Within the last decade,there has been a significant increase in the research and development of innovative NDE techniques to improve data processing and promote efficient and accurate infrastructure assessment.This paper aims to review one of those methods,namely,Infrared Thermography(IRT),and its applications in civil infrastructure.A comprehensive review is presented by investigating numerous journal articles,research papers,and technical reports describing numerous IRT applications for bridges,buildings,and general civil structures made from different materials.The capability of IRT to identify and pinpoint anomalies,typically in the early stages of degradation,has excellent potential to improve the safety and shore up the dependability of civil infrastructures while reducing expenses tied to maintenance and rehabilitation.Furthermore,the non-invasive nature of IRT is beneficial in mitigating disturbances and downtime that may occur during various inspection procedures.It is highlighted that IRT is a highly versatile and effective tool for infrastructure condition assessment.With further advancement and fine-tuning of the available techniques,it is likely that IRT will continue to gain significant popularity in maintaining and monitoring civil infrastructure.
基金the National Natural Science Foundation of China(Nos.52171316 and 51479116)。
文摘Vortex-induced vibration of hydrofoils is concerned with structural safety and noise level in hydraulic machinery and marine engineering.The research on vibration characteristics under different operating conditions is significant.In this study,numerical simulations are conducted to investigate the vortex-induced vibration responses of an elastically suspended hydrofoil with blunt trailing edge in pitch direction.The work studies the effects of four parameters,namely the structural natural frequency,mass ratio,initial attack angle,and Reynolds number on vibration characteristics,with special emphasis on frequency lock-in.Results indicate that as the structural natural frequency changes,the vibration amplitude may increase substantially within a certain frequency range,in which the vortex shedding frequency locks into the structural natural frequency,and frequency lock-in occurs.In addition,with increasing the mass ratio,the frequency range of lock-in becomes narrower,and both the upper and lower thresholds decrease.As the initial attack angle increases from 0◦to 6◦,the lock-in range gets reduced.Over the three Reynolds numbers(6×10^(5),9×10^(5),and 12×10^(5)),the lock-in range remains virtually unchanged.Moreover,for a certain structural natural frequency,modifying the mass ratio,initial attack angle,and Reynolds number could effectively suppress the vibration amplitude.
基金Zhongshan Science and Technology Bureau Project“The Application of Infrared Thermography in the Syndrome Differentiation of Chaihu Guizhi Ganjiang Decoction”(Project No.2021B1066)Zhongshan Science and Technology Bureau Project“Exploring the Diagnostic Approach of the TCM Syndrome Type‘Chaihu Guizhi Ganjiang Decoction’Based on Infrared Thermal Imaging Systems and Digital Modeling Methods of Ancient and Modern Literature”(Project No.2022B1131)。
文摘Objective:To evaluate the use of infrared thermography technology for objective and quantitative syndrome differentiation and treatment in traditional Chinese medicine(TCM),specifically in patients with Chaihu Guizhi Ganjiang Decoction syndrome.Methods:Data were collected from over 100 patients diagnosed with Chaihu Guizhi Ganjiang Decoction syndrome at Professor Li Leyu’s endocrinology clinic,Zhongshan Hospital of Traditional Chinese Medicine,Guangdong Province,between April 2021 and April 2022.Body surface temperature data were obtained using the MTI-EXPRO-2013-B infrared thermography system.Principal component analysis(PCA)was applied to differentiate temperature distribution characteristics between genders,and a neural network prediction model was constructed for syndrome diagnosis.Results:Infrared thermography effectively captured surface temperature characteristics of patients with Chaihu Guizhi Ganjiang Decoction syndrome.PCA identified one principal component with a variance explanation rate of 73.953%for females and two principal components with a cumulative variance explanation rate of 77.627%for males.The neural network model demonstrated high predictive performance,with an area under the ROC curve of 0.9743 for the training set and 0.9889 for the validation set.Sensitivity was 1,specificity 0.8636,precision 0.8846,accuracy 0.9333,and the F1 score 0.9388.Conclusion:Infrared thermography provides an innovative,objective,and quantitative method for syndrome differentiation and treatment in TCM.It represents a significant advancement in transitioning from traditional empirical approaches to modern,visualized,and precise diagnosis and treatment.This study underscores the potential of integrating advanced technologies in TCM for enhanced clinical application and modernization.
文摘高速铁路轮轨系统在服役过程中产生的疲劳裂纹是威胁行车安全的重大隐患。传统的无损检测方法难以有效识别处于闭合或半闭合状态的早期微小裂纹,尤其是在列车运行载荷作用下的动态工况。针对这一挑战,本文提出并系统研究了一种基于涡流脉冲热成像(Eddy Current Pulsed Thermography,ECPT)技术的轮轨疲劳裂纹检测方法。研究首先构建了负载作用下的非稳态疲劳裂纹多物理场模型,通过有限元仿真与实验相结合,深入探究了局部接触(闭合)裂纹的涡流-热响应机理,并揭示了裂纹闭合深度与表面温度场特征(如等温线内凹现象)之间的定量关系。在此基础上,自主研制了适用于车轮与钢轨的动态ECPT检测平台及专用磁轭传感器,并开展了高铁轮轨实物的动态检测试验。结果表明,所提方法不仅能有效区分开口与闭合裂纹,还能对不同深度、不同尺寸的疲劳裂纹进行可靠检出,检出深度范围可达0.35mm至5mm。结合主成分分析(PCA)与张量分解等图像增强算法,显著提升了缺陷的信噪比与可视化效果,为高铁轮轨疲劳裂纹的在线、高效、精准检测提供了重要的理论依据与技术支撑。
基金Project(51305292)supported by the National Natural Science Foundation of ChinaProject(20105429001)supported by the National Aeronautical Science Foundation of China
文摘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.
基金Project (51074181) supported by the National Natural Science Foundation of ChinaProject (2010ssxt241) supported by Precious Dissertation Innovation Foundation of Central South University, China
文摘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.
