Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize...Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.展开更多
During manufacturing and operation, different kinds of defects, e.g., delamination or surface cracks, may be generated in the plasma-facing components (PFCs) of a Tokamak device. To ensure the safety of the PFCs, vari...During manufacturing and operation, different kinds of defects, e.g., delamination or surface cracks, may be generated in the plasma-facing components (PFCs) of a Tokamak device. To ensure the safety of the PFCs, various kinds of nondestructive testing (NDT) techniques are needed for different defect and failure mode. This paper gives a review of the recently developed ultrasonic testing (UT) and laser thermography methods for inspection of the delamination and surface cracks in PFCs. For monoblock W/Cu PFCs of divertor, the bonding quality at both W-Cu and Cu- CuCrZr interfaces was qualified by using UT with a focus probe during manufacturing. A noncontact, coupling-free and flexible ultrasonic scanning testing system with use of an electromagnetic acoustic transducer and a robotic inspection manipulator was introduced then for the in-vessel inspection of delamination defect in first wall (FW). A laser infrared thermography testing method is highlighted for the on-line inspection of delamination defect in FW through the vacuum vessel window of the Tokamak reactor. Finally, a new laser spot thermography method using laser spot array source was described for the online inspection of the surface cracks in FW.展开更多
The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analy...The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analyzed.On this basis,a physical laser line scanning model is proposed.Afterwards,based on Fourier transform(FT)and segregation variablemethod(SVM),the heat conduction differential equation in laser line scanning thermography is derived in detail.The temperature field of the composite-based coatings model with defects is simulated numerically.The results show that the laser line scanning thermography can effectively detect the defects in the model.The correctness of the analytical calculation is verified by comparing the surface temperature distribution obtained by analytical calculation and numerical simulation.Additionally,an experiment is carried out and the changeable surface temperature obtained by analytical calculation is compared with the experimental results.It shows that the error of maximum temperature obtained by analytical calculation and by experiment is 8%with high accuracy,which proves the correctness of analytical calculation and enriches the theoretical foundation of laser line scanning thermography.展开更多
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 a...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.展开更多
Background:To date,there has been a great lack of investigation on the influence of age on blood flow and temperature of acupoints in specific regions.Objective:This study aimed to determine the association between di...Background:To date,there has been a great lack of investigation on the influence of age on blood flow and temperature of acupoints in specific regions.Objective:This study aimed to determine the association between different age categories and acupoint blood flow/temperature on the forearm.Methods:Acupoint blood flow and temperature were measured in healthy adults of different age categories using laser doppler flowmetry(LDF)and infrared thermography(IRT),respectively.A total of 60 eligible healthy volunteers were divided into the young group,mid age group and old age group.All groups received LDF and IRT examination.Shenmen(HT7),Shaohai(HT3),Taiyuan(LU9)and Chize(LU5)of the Heart and Lung meridians on the forearm were selected as 4 test acupoints.Results:Regarding blood flow of the 4 test acupoints,the PU of Taiyuan(LU9)in the old age group was sig-nificantly different compared with that of the young age group(P<0.05)and the mid age group(P<0.05),while there was no significant difference in PU of the other acupoints between 3 groups(all P>0.05).Simi-larly,regarding acupoint temperature of the 4 test sites,the temperature of Shaohai(HT3)in the old age group was significantly different compared with that of the mid age group(P<0.05),while there was no significant difference in the temperature of the other 3 acupoints between 3 age groups(all P>0.05).Conclusion:Age category tends to have notable influence on the blood flow and temperature in specific acupoints in the forearm.Therefore,particular concerns should be taken into consideration regarding the effect of age differences for future studies in this field.Nevertheless,further studies with a large sample size and more test acupoints are needed to further verify current findings.展开更多
基金supported by the National Key Scientific Instrument and Equipment Development Projects,China(Grant No.2013YQ470767)。
文摘Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.
基金the National Magnetic Confinement Fusion Program of China(Grant 2013GB113005)the National Natural Science Foundation of China(Grants51577139 and 11502192)for funding
文摘During manufacturing and operation, different kinds of defects, e.g., delamination or surface cracks, may be generated in the plasma-facing components (PFCs) of a Tokamak device. To ensure the safety of the PFCs, various kinds of nondestructive testing (NDT) techniques are needed for different defect and failure mode. This paper gives a review of the recently developed ultrasonic testing (UT) and laser thermography methods for inspection of the delamination and surface cracks in PFCs. For monoblock W/Cu PFCs of divertor, the bonding quality at both W-Cu and Cu- CuCrZr interfaces was qualified by using UT with a focus probe during manufacturing. A noncontact, coupling-free and flexible ultrasonic scanning testing system with use of an electromagnetic acoustic transducer and a robotic inspection manipulator was introduced then for the in-vessel inspection of delamination defect in first wall (FW). A laser infrared thermography testing method is highlighted for the on-line inspection of delamination defect in FW through the vacuum vessel window of the Tokamak reactor. Finally, a new laser spot thermography method using laser spot array source was described for the online inspection of the surface cracks in FW.
基金supported by the National Natural Science Foundation of China(Grant No.52005495).
文摘The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analyzed.On this basis,a physical laser line scanning model is proposed.Afterwards,based on Fourier transform(FT)and segregation variablemethod(SVM),the heat conduction differential equation in laser line scanning thermography is derived in detail.The temperature field of the composite-based coatings model with defects is simulated numerically.The results show that the laser line scanning thermography can effectively detect the defects in the model.The correctness of the analytical calculation is verified by comparing the surface temperature distribution obtained by analytical calculation and numerical simulation.Additionally,an experiment is carried out and the changeable surface temperature obtained by analytical calculation is compared with the experimental results.It shows that the error of maximum temperature obtained by analytical calculation and by experiment is 8%with high accuracy,which proves the correctness of analytical calculation and enriches the theoretical foundation of laser line scanning thermography.
文摘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.
基金The study was financially supported by the National Key R&D Pro-gram of China(NO.2018YFC1704600)Zhejiang Province Top Dis-cipline of Chinese Medicine(No.ZTK2017A03,No.ZTK2017A04).
文摘Background:To date,there has been a great lack of investigation on the influence of age on blood flow and temperature of acupoints in specific regions.Objective:This study aimed to determine the association between different age categories and acupoint blood flow/temperature on the forearm.Methods:Acupoint blood flow and temperature were measured in healthy adults of different age categories using laser doppler flowmetry(LDF)and infrared thermography(IRT),respectively.A total of 60 eligible healthy volunteers were divided into the young group,mid age group and old age group.All groups received LDF and IRT examination.Shenmen(HT7),Shaohai(HT3),Taiyuan(LU9)and Chize(LU5)of the Heart and Lung meridians on the forearm were selected as 4 test acupoints.Results:Regarding blood flow of the 4 test acupoints,the PU of Taiyuan(LU9)in the old age group was sig-nificantly different compared with that of the young age group(P<0.05)and the mid age group(P<0.05),while there was no significant difference in PU of the other acupoints between 3 groups(all P>0.05).Simi-larly,regarding acupoint temperature of the 4 test sites,the temperature of Shaohai(HT3)in the old age group was significantly different compared with that of the mid age group(P<0.05),while there was no significant difference in the temperature of the other 3 acupoints between 3 age groups(all P>0.05).Conclusion:Age category tends to have notable influence on the blood flow and temperature in specific acupoints in the forearm.Therefore,particular concerns should be taken into consideration regarding the effect of age differences for future studies in this field.Nevertheless,further studies with a large sample size and more test acupoints are needed to further verify current findings.
