RESUMO
Local strain measurements are considered as an effective method for structural health monitoring of high-temperature components, which require accurate, reliable and durable sensors. To develop strain sensors that can be used in higher temperature environments, an improved metal-packaged strain sensor based on a regenerated fiber Bragg grating (RFBG) fabricated in hydrogen (H2)-loaded boron-germanium (B-Ge) co-doped photosensitive fiber is developed using the process of combining magnetron sputtering and electroplating, addressing the limitation of mechanical strength degradation of silica optical fibers after annealing at a high temperature for regeneration. The regeneration characteristics of the RFBGs and the strain characteristics of the sensor are evaluated. Numerical simulation of the sensor is conducted using a three-dimensional finite element model. Anomalous decay behavior of two regeneration regimes is observed for the FBGs written in H2-loaded B-Ge co-doped fiber. The strain sensor exhibits good linearity, stability and repeatability when exposed to constant high temperatures of up to 540 °C. A satisfactory agreement is obtained between the experimental and numerical results in strain sensitivity. The results demonstrate that the improved metal-packaged strain sensors based on RFBGs in H2-loaded B-Ge co-doped fiber provide great potential for high-temperature applications by addressing the issues of mechanical integrity and packaging.
RESUMO
BACKGROUND & OBJECTIVE: Angiography, a common method in evaluating blood supply of lung carcinoma, is invasive and complicated, with low success rate for bronchial artery, and could not assure to show all supply blood vessels at a time. This study was to explore clinical value of 16 slices spiral CT angiography with 3-dimensional CT (3DCT) and CT virtual endoscopy (CTVE) in diagnosing and evaluating supply blood vessels and blood supply of lung carcinoma, so as to find a non-invasive, safe, simple and effective method in diagnosing blood supply of lung carcinoma. METHODS: A total of 72 patients with pathologically proved lung carcinoma underwent 16 slices spiral CT angiography with 3DCT. Volume rendering (VR), maximum intensity projection (MIP), and surface shaded display (SSD) of supply blood vessels of lung carcinoma were used as 3DCT models. CTVE of bronchial artery was performed in 25 patients. Color VR of tumor lesion was performed in all patients. RESULTS: Supply blood vessels were showed in 68 patients, 59 of them showed only bronchial artery, 5 showed intercostals arteries, and 4 showed mixed types, including bronchial artery, intercostals arteries, or branch arteries of subclavian artery. The bronchial artery entered into enlarged mediastinal lymph nodes in 4 patients. CTVE well displayed the orifice and lumen of bronchial arteries in the 25 patients. The extent of red color of tumor lesion on VR color image were divided into 4 types: no color (n=11), light red (n=17), moderate red (n=32), and heavy red (n=12); the added CT values of tumor lesion after enhanced CT were (6.16+/-2.23) Hu, (15.71+/-3.13) Hu, (25.47+/-2.71) Hu, and (44.31+/-19.68) Hu, respectively. The corresponding rate between enhanced type and distributive type of red color on color VR was 86.1%. CONCLUSIONS: The 16 slices spiral CT angiography with 3DCT and CTVE could show clearly supply blood vessels and blood supply of lung carcinoma. It is a non-invasive, simple and effective method in evaluating and diagnosing blood supply of lung carcinoma.
