Effects of the Ground Resolution and Thresholding on Crack Width Measurements.

When diagnosing the condition of a structure, it is necessary to measure the widths of any existing cracks in the structure. To ensure safety when relying on images of cracks, the selected imaging parameters and processing technology must be well understood. In this study, the effects of the ground sample distance and threshold values on the crack width measurement error are analyzed from a theoretical perspective.

Cardiac and Pericardial F-FDG Uptake on Oncologic PET/CT: Comparison with Echocardiographic Findings.

Background: Interpretation of cardiac uptake on 18-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) is often confounded by intense physiological FDG uptake and numerous benign conditions. The aim of the study was to describe the echocardiographic features in concordance with cardiac and pericardial F-FDG uptake on whole-body oncology PET/CT.

Methods: We enrolled 43 consecutive patients (34 solid tumors, 8 lymphomas and 1 leukemia) who were newly diagnosed with non-cardiac malignancy showing incidental cardiac or pericardial F-FDG uptake on PET/CT and underwent transthoracic Doppler echocardiography (TTE) within 1 month of PET/CT.

Analysis of Crack Image Recognition Characteristics in Concrete Structures Depending on the Illumination and Image Acquisition Distance through Outdoor Experiments.

The effects of illumination and shooting distance on crack image recognition were investigated by examining cracks in images taken with a camera. In order to examine the effects, images of cracks in a concrete structure taken while varying the illumination and shooting distance in an outdoor environment were analyzed. The images were acquired at a daytime illumination of 52,000 lx and a night illumination of 13 lx.

Observation of narrowband intrinsic spectra of Brillouin dynamic gratings.

We experimentally demonstrate that the reflection spectrum of a Brillouin dynamic grating in a polarization-maintaining fiber can be much narrower than the intrinsic linewidth of the stimulated Brillouin scattering, matching well with the theory of a fiber Bragg grating in terms of the linewidth and the reflectivity. A 3 dB bandwidth as narrow as 10.5 MHz is observed with the Brillouin dynamic grating generated in a 9 m uniform fiber.

High-resolution Brillouin optical time domain analysis based on Brillouin dynamic grating.

We propose and experimentally demonstrate a high-resolution distributed measurement of the Brillouin gain spectrum in a polarization-maintaining fiber (PMF) using Brillouin dynamic grating. In our approach, acoustic waves which contain the information of the local Brillouin frequency are generated by a long pump pulse in one polarization along the PMF and are read out by a short probe pulse with an orthogonal polarization at a different optical frequency from the pump. In experiments, a distributed strain measurement with a 10 cm spatial resolution is demonstrated in a 105 m PMF.