绝缘子是电力系统中最常见的设备,绝缘子故障将直接威胁系统的稳定性和安全性。红外成像技术具有非接触,无损的优点,可以有效地监控和评估绝缘子的状况。在红外图像中检测绝缘子的位置并提取绝缘子是自动诊断的关键步骤。为了在复杂的...绝缘子是电力系统中最常见的设备,绝缘子故障将直接威胁系统的稳定性和安全性。红外成像技术具有非接触,无损的优点,可以有效地监控和评估绝缘子的状况。在红外图像中检测绝缘子的位置并提取绝缘子是自动诊断的关键步骤。为了在复杂的航拍图像中提取方向不同的多个绝缘子,提出将改进环投影算法IRPT(Improved Ring Projection Transformation)和局部动态时间规整算法LDTW(Local Dynamic Time Warping)相结合,从而准确定位绝缘子,再提取纯粹的绝缘子,为后续诊断绝缘子故障奠定基础。使用大量的真实航拍图像作为实验图像,结果表明,该方法能够在低分辨率、复杂背景的红外图像中提取出方位不同的多个绝缘子。展开更多
As promising light-weight and high-performance structure components, large-diameter thin-walled （LDTW） Ti 6Al^4V titanium alloy （TC4） bent tubes are needed most urgently in many industries such as aviation and aer...As promising light-weight and high-performance structure components, large-diameter thin-walled （LDTW） Ti 6Al^4V titanium alloy （TC4） bent tubes are needed most urgently in many industries such as aviation and aerospace. Warm bending may be a feasible way for manufacturing these components. Understanding their temperature and strain rate dependent tensile behavior is the foundation for formability improvement and warm bending design. In this paper, uniaxial ten- sile tests were conducted at elevated temperatures ranging from 298 K to 873 K at tensile velocities of 2, 10, 15 mm/min. The main results show that the tensile behavior of LDTW TC4 tubes is dif- ferent from that of TC4 sheets. The typical elongation of TC4 tubes at room temperature is 10% lower than that of TC4 sheets. The flow stress of TC4 tubes decreases greatly by about 50% with the temperature rising to 873 K. At temperatures of 573-673 K, the hardening exponent is at its highest value, which means the deformation mechanism changes from twining to more dislocation movement by slipping. The fracture elongation of TC4 tubes fluctuates with increasing temperature, which is associated with changes in the deformation mechanism and with the blue brittleness. The fractography of TC4 tubes at various temperatures, especially at 673 K, shows that second phases and impurities significantly influence fracture elongation. By considering the characteristics of the tensile behavior and by properly choosing the die material, the warm bending for TC4 tubes can be achieved at temperatures of 723-823 K.展开更多
文摘绝缘子是电力系统中最常见的设备,绝缘子故障将直接威胁系统的稳定性和安全性。红外成像技术具有非接触,无损的优点,可以有效地监控和评估绝缘子的状况。在红外图像中检测绝缘子的位置并提取绝缘子是自动诊断的关键步骤。为了在复杂的航拍图像中提取方向不同的多个绝缘子,提出将改进环投影算法IRPT(Improved Ring Projection Transformation)和局部动态时间规整算法LDTW(Local Dynamic Time Warping)相结合,从而准确定位绝缘子,再提取纯粹的绝缘子,为后续诊断绝缘子故障奠定基础。使用大量的真实航拍图像作为实验图像,结果表明,该方法能够在低分辨率、复杂背景的红外图像中提取出方位不同的多个绝缘子。
基金support of the National Natural Science Foundation of China(No.51275415 and No.50905144)the program for New Century Excellent Talents in University+2 种基金the Natural Science Basic Research Plan in Shaanxi Province(No.2011JQ6004)of Chinathe fund of the State Key Laboratory of Solidification Processing in NWPU of Chinathe 111 Project(No.B08040)of China
文摘As promising light-weight and high-performance structure components, large-diameter thin-walled （LDTW） Ti 6Al^4V titanium alloy （TC4） bent tubes are needed most urgently in many industries such as aviation and aerospace. Warm bending may be a feasible way for manufacturing these components. Understanding their temperature and strain rate dependent tensile behavior is the foundation for formability improvement and warm bending design. In this paper, uniaxial ten- sile tests were conducted at elevated temperatures ranging from 298 K to 873 K at tensile velocities of 2, 10, 15 mm/min. The main results show that the tensile behavior of LDTW TC4 tubes is dif- ferent from that of TC4 sheets. The typical elongation of TC4 tubes at room temperature is 10% lower than that of TC4 sheets. The flow stress of TC4 tubes decreases greatly by about 50% with the temperature rising to 873 K. At temperatures of 573-673 K, the hardening exponent is at its highest value, which means the deformation mechanism changes from twining to more dislocation movement by slipping. The fracture elongation of TC4 tubes fluctuates with increasing temperature, which is associated with changes in the deformation mechanism and with the blue brittleness. The fractography of TC4 tubes at various temperatures, especially at 673 K, shows that second phases and impurities significantly influence fracture elongation. By considering the characteristics of the tensile behavior and by properly choosing the die material, the warm bending for TC4 tubes can be achieved at temperatures of 723-823 K.
