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Joint Scanning Laser Thermography Defect Detection Method for Carbon Fiber Reinforced Polymer
摘要： In this paper, a new inspection method, joint scanning laser thermography (JSLT) as well as its data reconstruction and processing algorithm, is proposed. The new inspection method is utilized to detect and characterize the flat-bottom holes (FBH) in carbon fiber composites by using joint laser scanning scheme. By analyzing the nature of the thermal image sequences sampled under such a scanning scheme, a quick and simple reconstruction method is developed to characterize the buried depth of defects based on 1D heat conduction model. The processed thermal images are expected to get higher temporal resolution and spatial resolution. It can inspect larger area within shorter acquisition time than the pulse thermography. Thus, the study solves the dilemma between the inspection speed and the inspection capacity. Later, a joint laser scanning thermography test is set up to test the algorithm on a carbon fiber composite panel with defects buried at different depth. The experimental results show that the reconstructed data almost behave as those under pulse excitation. The tendency of temperature to change in the logarithmic domain over time is similar to the curve in the TSR method. But, unlike the pulse thermography data, the defect detection rate of PCA based on reconstructed data is higher than that of independent component analysis (ICA) and FFT phase image. The JSLT system is used to detect FBH and the diameter-depth ratio reached 3.33.
关键词： data reconstruction,scanning laser,defect detection,thermography,NDT
更新于2025-09-12 10:27:22
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[IEEE 2019 4th International Conference on Smart and Sustainable Technologies (SpliTech) - Split, Croatia (2019.6.18-2019.6.21)] 2019 4th International Conference on Smart and Sustainable Technologies (SpliTech) - An Online Novel Two-Layered Photovoltaic Fault Monitoring Technique Based Upon The Hybrid Parameters
摘要： The utility-scale photovoltaic power plants are facing unique challenges compared to the traditional fossil fuel-based power plant in terms of faults localization, diversity, and frequency. The complex nature of faults raises serious concerns about grid-connectivity of photovoltaic plants in terms of operability, power quality, grid stability, and breakdown vulnerability. One of the predominant problems concerning utility-scale photovoltaic power plants remains in the variety, frequency, and nature of faults occurring during operation. In this research work, an online novel cost-effective two-layered fault monitoring scheme is introduced based upon the thermal and electrical signatures. The proposed scheme is implemented on a 1.6 kW photovoltaic array and various faults (short circuit, open circuit, and ground fault) are induced in the photovoltaic modules. The scheme shows promising results in fault monitoring and classification without making any hardware modifications in the solar module. The proposed scheme is compared and validated through thermography and results indicates that the proposed fault monitoring scheme can monitor and characterize the faults effectively compared to traditional means through thermography.
关键词： Solar Photovoltaic,Fault Monitoring,Fault Detection,Ground Fault,Open Circuit Fault,Thermography,Short Circuit Fault
更新于2025-09-12 10:27:22
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Infrared Thermography and DIT of Quadcopter Rotor Blades Using Laser Heating
摘要： A measuring method to detect wall flow topologies by active infrared thermography was developed. Quadcopter rotor blades were studied in typical hover and forward flight conditions, while using a high-power infrared laser to heat the blade surface. By this, the distance between heat source and measuring object could be significantly increased compared to conventional heat sources. The resulting images show little blurring at high signal-to-noise ratios. In steady-state flow conditions, wall flow topologies could be detected reliably and show good agreement with performed oil-film interferometry measurements. Wind tunnel experiments at forward flight conditions were conducted and indicate unsteady shifts of the transition location.
关键词： laser heating,rotor blades,differential infrared thermography,boundary-layer transition,thermography,oil-film interferometry
更新于2025-09-11 14:15:04
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Infrared thermography and ulcer prevention in the high‐risk diabetic foot: data from a single‐blind multicentre controlled clinical trial
摘要： Aim To assess the usefulness of monthly thermography and standard foot care to reduce diabetic foot ulcer recurrence. Methods People with diabetes (n=110), neuropathy and history of ≥1 foot ulcer participated in a single-blind multicentre clinical trial. Feet were imaged with a novel thermal imaging device (Diabetic Foot Ulcer Prevention System). Participants were randomized to intervention (active thermography + standard foot care) or control (blinded thermography + standard foot care) and were followed up monthly until ulcer recurrence or for 12 months. Foot thermograms of participants from the intervention group were assessed for hot spots (areas with temperature ≥2.2°C higher than the corresponding contralateral site) and acted upon as per local standards. Results After 12 months, 62% of participants were ulcer-free in the intervention group and 56% in the control group. The odds ratios of ulcer recurrence (intervention vs control) were 0.82 (95% CI 0.38, 1.8; P=0.62) and 0.55 (95% CI 0.21, 1.4; P=0.22) in univariate and multivariate logistic regression analyses, respectively. The hazard ratios for the time to ulcer recurrence (intervention vs control) were 0.84 (95% CI 0.45, 1.6; P=0.58) and 0.67 (95% CI 0.34, 1.3; P=0.24) in univariate and multivariate Cox regression analyses, respectively. Conclusions Monthly intervention with thermal imaging did not result in a significant reduction in ulcer recurrence rate or increased ulcer-free survival in this cohort at high risk of foot ulcers. This trial has, however, informed the design of a refined study with longer follow-up and group stratification, further aiming to assess the efficacy of thermography to reduce ulcer recurrence.
关键词： ulcer prevention,diabetic foot ulcer,thermal imaging,neuropathy,thermography
更新于2025-09-11 14:15:04
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Techniques for Evaluating the Depth of a Crack by Means of Laser Spot Thermography
摘要： Laser Spot Thermography is a useful tool in nondestructive crack detection. Our goal is to estimate the depth of a fracture from external thermal measurements. First we transform a set of real 3D data in a 2D effective one. Then we use the 2D data set as input in different methods for solving an inverse problems for the heat equation. Our guiding idea is that an effort in the direction of the mathematical analysis of the problem, rewards us in term of computational costs.
关键词： laser-spot thermography,cracks,inverse problems
更新于2025-09-11 14:15:04
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Imaging and micro-structural characterization of moisture induced degradation in crystalline silicon photovoltaic modules
摘要： Moisture induced degradation in photovoltaic (PV) modules operate via multiple chemical mechanisms commonly identi?ed by the sole use of destructive techniques. However, in such cases, e?ective use of spatial imaging techniques can aid identi?cation of certain operating mechanisms on the basis of degradation pattern characteristics. This paper presents an approach of imaging the e?ects of moisture induced degradation in crystalline silicon PV modules under damp heat (DH) test conditions using electroluminescence (EL) and dark lock-in-thermography (DLIT) imaging techniques. The a?ected regions were extracted for identi?cation of degradation products using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) micro-structural characterization technique. Consequently, combination of both imaging and micro-structural characterization techniques were used to propose the mechanism of degradation. The presented approach was instrumental in identi?cation of the e?ects of moisture induced degradation through imaging techniques, moreover the investigation also provided insights in this ?eld of work. The results present signature image patterns for identi?cation and di?erentiation of dominant chemical mechanisms under moisture induced conditions viz. tin migration at the ?nger-wafer interface and formation of silver oxide at cell cracks and edges. The ribbon interconnects was identi?ed as an active site for deposition of oxides from solder material, and aluminium electrode in presence of water as an electrolyte. Moreover, loss in interfacial adhesion between wafer, encapsulant and ?nger. In addition, material quality, manufacturing distinctions, and module design parameters seem to be responsible for observing di?erent operating mechanisms. Also, the obtained insights were applied for investigation of a 20-year-old aged PV module.
关键词： Chemical degradation,Damp heat test,Photovoltaic modules,Electroluminescence imaging,Dark lock-in thermography imaging,Moisture induced degradation
更新于2025-09-11 14:15:04
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Laser-Induced Thermography for Quantitative Detection of Cracks in Building Materials
摘要： Laser-induced thermography is a an active technique using a laser source to heat a very small area on a side of a crack in a building material. The presence of a crack is easily detected as a sharp change in the temperature due to its insulating nature, but no information about its depth is directly available from the thermal image. The method described in this paper uses a heuristic form of the temperature on the surface of the heated specimen, which is transformed to a two-dimensional distribution. Then, a relation is used (called β-tool) between the thermal gap across the crack and the unknown depth of the damage. The purpose is that of making it possible to distinguish between shallow and deep fractures (more than 15mm deep).
关键词： laser-spot thermography,non-destructive evaluation,cracks
更新于2025-09-11 14:15:04
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Thermographic Monitoring of Laser Cutting Machine
摘要： Computer Numerical Controlled (CNC) laser cutting tools are developing as an alternative to conventional cutting systems thanks to increased accuracy, non-contact processing, higher productivity, less energy demand. An IR camera is utilized to monitor the laser cutting process of a steel plate. Even though the process is very complicated an analytical solution of the temperature ?eld generated on a slab by a point source moving along one direction of the plate surface is provided in order to interpret the temperature ?eld experimentally obtained by the IR camera.
关键词： mechanical properties,laser cutting machine,IR thermography
更新于2025-09-11 14:15:04
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Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques
摘要： There is a wealth of existing experimental data of flames collected using laser diagnostics. The primary objective of this review is to provide context and guidance in interpreting these laser diagnostic data. This educational piece is intended to benefit those new to laser diagnostics or with specialization in other facets of combustion science, such as computational modeling. This review focuses on laser-diagnostics in the context of the commonly used canonical jet-in-hot-coflow (JHC) burner, although the content is applicable to a wide variety of configurations including, but not restricted to, simple jet, bluff body, swirling and stratified flames. The JHC burner configuration has been used for fundamental studies of moderate or intense low oxygen dilution (MILD) combustion, autoignition and flame stabilization in hot environments. These environments emulate sequential combustion or exhaust gas recirculation. The JHC configuration has been applied in several burners for parametric studies of MILD combustion, flame reaction zone structure, behavior of fuels covering a significant range of chemical complexity, and the collection of data for numerical model validation. Studies of unconfined JHC burners using gaseous fuels have employed point-based Rayleigh-Raman or two-dimensional Rayleigh scattering measurements for the temperature field. While the former also provides simultaneous measurements of major species concentrations, the latter has often been used in conjunction with planar laser-induced fluorescence (PLIF) to simultaneously provide quantitative or qualitative measurements of radical and intermediary species. These established scattering-based thermography techniques are not, however, effective in droplet or particle laden flows, or in confined burners with significant background scattering. Techniques including coherent anti-Stokes Raman scattering (CARS) and non-linear excitation regime two-line atomic fluorescence (NTLAF) have, however, been successfully demonstrated in both sooting and spray flames. This review gives an overview of diagnostics techniques undertaken in canonical burners, with the intention of providing an introduction to laser-based measurements in combustion. The efficacy, applicability and accuracy of the experimental techniques are also discussed, with examples from studies of flames in JHC burners. Finally, current and future directions for studies of flames using the JHC configuration including spray flames and studies and elevated pressures are summarized.
关键词： moderate or intense low oxygen dilution (MILD) combustion,autoignition,vitiated coflow burner (VCB),laser-induced fluorescence (LIF),thermography,jet in hot coflow (JHC),planar laser diagnostics
更新于2025-09-11 14:15:04
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Intelligent classification of silicon photovoltaic cell defects based on eddy current thermography and convolution neural network
摘要： Defects the production process of silicon photovoltaic (Si-PV) cells are urgently needed to be detected due to their serious impact on the normal generation of PV system. In view of the shortcomings such as low defect efficiency, few detection data and high detection error rate in the existing industrial production line, the main research purpose of this study is to complete an intelligent classification method for efficient and innovative defect detection for Si-PV cells and modules. The purpose is to improve the detection efficiency of Si-PV cell, to ensure the safety and reliability of Si-PV cell production process, to achieve large number of Si-PV cell defects detection and classification. Firstly, the Eddy Current Thermography (ECT) system of Si-PV cells was established. Secondly, Principal Component Analysis (PCA), Independent Component Analysis (ICA) and Non-negative Matrix Factorization (NMF) algorithms are compared for thermography sequences processing. Thirdly, LeNet-5, VGG-16 and GoogleNet models are compared for Si-PV cell defects classification. Finally, the results showed that the proposed method have successful application in Si-PV cell defects detection and classification.
关键词： Nondestructive testing & evaluation,Defect feature extraction,Defect classification,Convolution neural network,Silicon photovoltaic cell,Eddy current thermography
更新于2025-09-11 14:15:04