Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence an...Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence and measure their depths. This technique needs to be direct contact between the probe and the rail head, with a coupling fluid in at the interface. Other weaknesses of these ultrasonic techniques include false detections as well as missed detections. Infrared thermography is a relatively new non-destructive inspection technique used for a wide range of applications but is not used for rail squat detection. Lock-in thermography is a non-destructive inspection technique that can be used for the detection of near surface defects. It utilizes an infrared camera to detect the thermal waves and then produces a thermal image, which displays the local thermal wave variation in phase or amplitude. In inhomogeneous materials, the amplitude and phase of the thermal wave carries information related to both the local thermal properties and the nature of the structure being inspected. This comparison is then used to determine the phase angle difference (Δf) between the input and the thermal response of the object. The aim of this paper is to determine whether lock-in thermography can be used to firstly locate squats in rails, and secondly measure their depths. It has demonstrated the feasibility for using such a technique in generating thermal responses that could be adequately utilized for the purpose of defect characterization.展开更多
Breast cancer is the second leading cause of death in women.It occurs when cells in the breast start to grow out of proportion and invade neighboring tissues or spread throughout the body.Mammography is one of the mos...Breast cancer is the second leading cause of death in women.It occurs when cells in the breast start to grow out of proportion and invade neighboring tissues or spread throughout the body.Mammography is one of the most effective and popular modalities presently used for breast cancer screening and detection.Efforts have been made to improve the accuracy of breast cancer diagnosis using different imaging modalities.Ultrasound and magnetic resonance imaging have been used to detect breast cancers in high risk patients.Recently,electrical impedance imaging and nuclear medicine techniques are also being widely used for breast cancer screening and diagnosis.In this paper,we discuss the capabilities of various breast imaging modalities.展开更多
文摘Rail squats are a form of near surface rolling contact fatigue damage found in rail heads. Currently, the most popular method to detect the rail squats is utilizing ultrasonic techniques to determine their presence and measure their depths. This technique needs to be direct contact between the probe and the rail head, with a coupling fluid in at the interface. Other weaknesses of these ultrasonic techniques include false detections as well as missed detections. Infrared thermography is a relatively new non-destructive inspection technique used for a wide range of applications but is not used for rail squat detection. Lock-in thermography is a non-destructive inspection technique that can be used for the detection of near surface defects. It utilizes an infrared camera to detect the thermal waves and then produces a thermal image, which displays the local thermal wave variation in phase or amplitude. In inhomogeneous materials, the amplitude and phase of the thermal wave carries information related to both the local thermal properties and the nature of the structure being inspected. This comparison is then used to determine the phase angle difference (Δf) between the input and the thermal response of the object. The aim of this paper is to determine whether lock-in thermography can be used to firstly locate squats in rails, and secondly measure their depths. It has demonstrated the feasibility for using such a technique in generating thermal responses that could be adequately utilized for the purpose of defect characterization.
文摘Breast cancer is the second leading cause of death in women.It occurs when cells in the breast start to grow out of proportion and invade neighboring tissues or spread throughout the body.Mammography is one of the most effective and popular modalities presently used for breast cancer screening and detection.Efforts have been made to improve the accuracy of breast cancer diagnosis using different imaging modalities.Ultrasound and magnetic resonance imaging have been used to detect breast cancers in high risk patients.Recently,electrical impedance imaging and nuclear medicine techniques are also being widely used for breast cancer screening and diagnosis.In this paper,we discuss the capabilities of various breast imaging modalities.
