Multi-Excitation Infrared Fusion for Impact Evaluation of Aluminium-BFRP/GFRP Hybrid Composites.

Fibre metal laminates are widely implemented in the aerospace industry owing to the merits of fatigue resistance and plastic properties. An effective defect assessment technique needs to be investigated for this type of composite materials. In order to achieve accurate impact-induced damage evaluation, a multi-excitation infrared fusion method is introduced in this study. Optical excitation thermography with high performance on revealing surface and subsurface defects is combined with vibro-thermography to improve the capability of detection on defects. Quantitative analysis is carried out on the temperature curve to assess the impact-induced deformation. A new image fusion framework including feature extraction, feature selection and fusion steps is proposed to fully utilize the information from two excitation modalities. Six fibre metal laminates which contain aluminium-basalt fibre reinforced plastic and aluminium-glass fibre reinforced plastic are investigated. Features from different perspectives are compared and selected via intensity contrast on deformation area for fusion imaging. Both types of defects (i.e., surface and sub-surface) and the internal deformation situation of these six samples are characterized clearly and intuitively.

Enhanced Infrared Sparse Pattern Extraction and Usage for Impact Evaluation of Basalt-Carbon Hybrid Composites by Pulsed Thermography.

Nowadays, infrared thermography, as a widely used non-destructive testing method, is increasingly studied for impact evaluation of composite structures. Sparse pattern extraction is attracting increasing attention as an advanced post-processing method. In this paper, an enhanced sparse pattern extraction framework is presented for thermographic sequence processing and defect detection. This framework adapts cropping operator and typical component extraction as a preprocessing step to reduce the dimensions of raw data and applies sparse pattern extraction algorithms to enhance the contrast on the defect area. Different cases are studied involving several defects in four basalt-carbon hybrid fiber-reinforced polymer composite laminates. Finally, comparative analysis with intensity distribution is carried out to verify the effectiveness of contrast enhancement using this framework.

Measuring the Water Content in Wood Using Step-Heating Thermography and Speckle Patterns-Preliminary Results.

The relationship between wood and its degree of humidity is one of the most important aspects of its use in construction and restoration. The wood presents a behavior similar to a sponge, therefore, moisture is related to its expansion and contraction. The nondestructive evaluation (NDE) of the amount of moisture in wood materials allows to define, e.g., the restoration procedures of buildings or artworks. In this work, an integrated study of two non-contact techniques is presented. Infrared thermography (IRT) was able to retrieve thermal parameters of the wood related to the amount of water added to the samples, while the interference pattern generated by speckles was used to quantify the expansion and contraction of wood that can be related to the amount of water. In twenty-seven wooded samples, a known quantity of water was added in a controlled manner. By applying advanced image processing to thermograms and specklegrams, it was possible to determine fundamental values controlling both the absorption of water and the main thermophysical parameters that link the samples. On the one hand, results here shown should be considered preliminary because the experimental values obtained by IRT need to be optimized for low water contents introduced into the samples. On the other hand, speckle interferometry by applying an innovative procedure provided robust results for both high and low water contents.

Study on internal stress damage detection in long-distance oil and gas pipelines via weak magnetic method.

Weak magnetic stress detection is an important issue in oil-gas pipeline internal detection area. In order to verify the characteristics of weak magnetic stress internal detection signals, we built herein a magneto-mechanics equivalent model having a balanced magnetic field. First, we calculated the relationship between the stress and the weak magnetic signals; consequently, the analysis propagation laws of the weak magnetic signals with non-magnetic saturation were pointed out. Finally, the theoretical model was validated by a systematic experimental research. The analytical results show that a one-to-one linear link between the weak magnetic signals and the stress concentration is clear. Instead, the change of the weak magnetic signals with the liftoff is nonlinear, therefore we are proposing the Boltzmann liftoff correction factor whose degree of adaptability of the equivalent model can reach the value of 94%. It is possible to note that when the liftoff is in the approximate linear stage, the relevance ratio and the recognition rate of the magneto-mechanics curve show a high-quality. This conclusion is important in the engineering field for the set of the liftoff.

Impact of different final optimization techniques on long-term clinical outcomes of left main cross-over stenting.

BACKGROUND: The optimal final optimization technique to be used in patients after Cross Over Left main stenting remainsdebatable. AIM: We evaluate the impact of the post-optimization technique (POT), kissing balloon (KB) and the POT-side-POT techniques on both cardiovascular mortality and event-free survival in patients receiving left main (LM) cross-over stenting for an isolated/distal bifurcation LM disease. METHODS: Clinical and instrumental records of 128 consecutive patients (102 males, mean age 73.39 ±â€¯9.54 years old) with isolated distal/bifurcation LM disease and bypass surgery contraindications or refusal enrolled to receive LM cross-over stenting between the 1st January 2012 and the 1st January 2017 at two institutions: the Rovigo General Hospital (Rovigo, Italy) and the Alexandrovka Hospital University School of Medicine (Sofia, Bulgaria). Patients has been divided into three groups (POT, KB and POT-side-POT) according the optimal final optimization technique used while the 5-year cardiovascular mortality has been evaluated using the log-rank (Mantel-Cox) analysis. RESULTS: Baseline angiographic characteristics of the LM disease were mostly equivalent among the three groups. Over a global follow-up of 61.03 ±â€¯0.92 months, the rates of target vessel revascularization, acute myocardial infarction, and stent thrombosis, were not different among groups. Patients treated with POT had a slightly better long-term survival. CONCLUSIONS: None of these optimization techniques appeared to have clearly better long-term outcomes after LM Cross-over stenting in our retrospective study. POT resulted in a slightly better survival compared to Pot-sid-POT and KB.

Eddy current pulsed thermography for ballistic impact evaluation in basalt-carbon hybrid composite panels.

In this paper, eddy current pulsed thermography was used to evaluate ballistic impact damages in basalt-carbon hybrid fiber-reinforced polymer composite laminates for the first time, to our knowledge. In particular, different hybrid structures including intercalated stacking and sandwich-like sequences were used. Pulsed phase thermography, wavelet transform, principle component thermography, and partial least-squares thermography were used to process the thermographic data. Ultrasound C-scan testing and X-ray computed tomography were also performed for comparative purposes. Finite element analysis was used for validation. Finally, an analytical and comparative study was conducted based on signal-to-noise ratio analysis.

Usefulness of the Finet law to guide stent size selection in ostial left main stenting: Comparison with standard angiographic estimation.

BACKGROUNDS: Intravascular ultrasound has been suggested to optimize stent diameter and length in Left Main (LM) procedures, but in the real-world ostial LM stenting is often accomplished with angiography only guidance. The Finet law which regulates the fractal geometry of human bifurcation has the potential to increase the accuracy of stent-sizing. To retrospectively evaluating the impact on outcomes of the addition of Finet Law to standard quantitative coronary angiography (QCA) in guiding stent selection of ostial LM stenting compared to standard angiography estimation. METHODS: We retrospectively evaluated the clinical and instrumental records of patients with isolated ostial LM disease and bypass surgery contraindications or refusal as determined by the local Heart Team who received stenting from 1 January 2012 to 1 January 2017 at Rovigo General Hospital. Patients were discrimined on the basis of the addition to QCA angiographic evaluation of the Finet-law. RESULTS: Seventy-three patients (45 males, mean age 69.9 ±â€¯10.9 years old) ostial LM stenting, 36 patients using QCA and Finet law (QCA-Finet) and 37 using standard QCA angiographic (QCA-angio) evaluation of the vessel diameter. By QCA, vessel size, mean stent diameter at implantation and after post-dilatation were clearly bigger in the QCA+ Finet than QCA-angio (4.4 ±â€¯0.8 and 3.8 ±â€¯0.7, p < 0.001). At a mean follow-up of 5.0 ±â€¯0.4 years, cardiovascular mortality and cardiovascular events incidence were higher in QCA-angio compared to QCA+Finet group of patients. CONCLUSIONS: Our study suggested that adding the Finet law to standard angiography estimation of the LM stent size may improve long-term outcomes.