Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave pr...Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.展开更多
Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is stron...Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is strongly related to the existence of localized thermal stresses generated during the laser operation.These thermal stresses can overcome the yield strength of the materials forming the active part of the laser diode.Different factors contribute to reduce the laser power threshold for degradation.Among them the thermal transport across the laser structure constitutes a critical issue for the reliability of the device.展开更多
电力设备运维过程中积累了大量缺陷图像与文本数据,这些数据对指导电力设备故障诊断及维护决策具有重要意义。针对现有电力设备缺陷分类任务中数据形式单一、融合层次浅、数据质量差等问题,该文提出了一种基于改进注意力机制和对比学习...电力设备运维过程中积累了大量缺陷图像与文本数据,这些数据对指导电力设备故障诊断及维护决策具有重要意义。针对现有电力设备缺陷分类任务中数据形式单一、融合层次浅、数据质量差等问题,该文提出了一种基于改进注意力机制和对比学习的图文融合分类方法(image-text fusion classification method based on improved attention mechanism and contrastive learning,IAC-ITFusion)。首先,该方法设计了一种双循环跨模态注意力机制(dual-cycle cross-modal attention,DCCA),用于捕捉图文数据映射关系的同时整合特征信息。其次,基于对比学习的思想,提出了一种注意力引导损失函数,用于调控DCCA机制的学习方向,使其聚焦于正确的特征信息,实现图文数据特征的有效融合。最后,针对电力线、变电站设备缺陷图文融合分类任务进行实验验证,结果显示所提方法准确率分别达到98.48%和98.57%,证明了该方法在电力设备缺陷图文融合分类任务上的有效性,对于推动电力设备运维智能化发展具有重要意义。展开更多
High laser-induced damage threshold and large aperture were focuses on the studies of high power laser coatings. This paper reports the research activities at our center. Several measures were developed for evaluating...High laser-induced damage threshold and large aperture were focuses on the studies of high power laser coatings. This paper reports the research activities at our center. Several measures were developed for evaluating characters of laser damage, including determination of laser induced damage threshold and detection of absorption based on surface thermal lensing technique. Defect was deemed to be the initial source of laser damage, and was the main factor restricting the laser damage resistance of optical coatings. The contribution of several kinds of typical defects to laser damage was analyzed, and some deposition measures were adopted to control and eliminate the origin of defect. Furthermore, some post-treatment methods were also employed to alleviate the influence of the defect and to improve the laser damage resistance. Correction mask was introduced to improve the thickness uniformity, and the thickness uniformity can be amended to less than 1% in the range of Φ650 mm. Preliminary investigation related to surface deformation was also conducted.展开更多
及时检测绝缘子自爆缺陷对输电线路安全可靠运行具有重要意义。针对深度学习模型对具有小目标特征的绝缘子自爆缺陷检测能力不足、模型结构复杂等问题,提出了一种基于轻量化改进YOLOv8n输电线路绝缘子自爆检测方法。以YOLOv8n网络为基...及时检测绝缘子自爆缺陷对输电线路安全可靠运行具有重要意义。针对深度学习模型对具有小目标特征的绝缘子自爆缺陷检测能力不足、模型结构复杂等问题,提出了一种基于轻量化改进YOLOv8n输电线路绝缘子自爆检测方法。以YOLOv8n网络为基础模型,通过添加小目标检测模块来捕捉绝缘子自爆的小目标细节信息,提高其检测能力;进一步,引入SIoU损失函数,解决原始CIoU损失函数未考虑真实框与预测框之间的方向问题,增强目标定位准确性;最后,使用通道剪枝方法,对改进模型进行剪枝,去除模型冗余参数、减少浮点运算量,降低模型计算成本和复杂度。在构建的绝缘子自爆数据集上的实验结果表明,轻量化改进方法的平均准确性均值达到97.1%,其浮点运算量和体积分别为4.9 G FLOPS和1.82 MB,仅为原始模型的60.5%和29.7%,合理兼顾了绝缘子自爆检测的准确性和模型复杂性。在另一个输电线路巡检数据集中,本研究方法对其他类型的小目标检测准确性也较好,具有良好的推广应用前景。展开更多
基金Supported by National Natural Science Foundation of China(Grant No51605229)Natural Science Foundation of Higher Education Institutions of Jiangsu Province,China(Grant No.16KJB460016)+1 种基金the“333”Project of Jiangsu Province,China(Grant No.BRA2015310)China Postdoctora Science Foundation(Grant No.2016M601844)
文摘Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.
基金funded by the Spanish Government(MAT-2010-20441-C02)
文摘Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is strongly related to the existence of localized thermal stresses generated during the laser operation.These thermal stresses can overcome the yield strength of the materials forming the active part of the laser diode.Different factors contribute to reduce the laser power threshold for degradation.Among them the thermal transport across the laser structure constitutes a critical issue for the reliability of the device.
文摘电力设备运维过程中积累了大量缺陷图像与文本数据,这些数据对指导电力设备故障诊断及维护决策具有重要意义。针对现有电力设备缺陷分类任务中数据形式单一、融合层次浅、数据质量差等问题,该文提出了一种基于改进注意力机制和对比学习的图文融合分类方法(image-text fusion classification method based on improved attention mechanism and contrastive learning,IAC-ITFusion)。首先,该方法设计了一种双循环跨模态注意力机制(dual-cycle cross-modal attention,DCCA),用于捕捉图文数据映射关系的同时整合特征信息。其次,基于对比学习的思想,提出了一种注意力引导损失函数,用于调控DCCA机制的学习方向,使其聚焦于正确的特征信息,实现图文数据特征的有效融合。最后,针对电力线、变电站设备缺陷图文融合分类任务进行实验验证,结果显示所提方法准确率分别达到98.48%和98.57%,证明了该方法在电力设备缺陷图文融合分类任务上的有效性,对于推动电力设备运维智能化发展具有重要意义。
文摘High laser-induced damage threshold and large aperture were focuses on the studies of high power laser coatings. This paper reports the research activities at our center. Several measures were developed for evaluating characters of laser damage, including determination of laser induced damage threshold and detection of absorption based on surface thermal lensing technique. Defect was deemed to be the initial source of laser damage, and was the main factor restricting the laser damage resistance of optical coatings. The contribution of several kinds of typical defects to laser damage was analyzed, and some deposition measures were adopted to control and eliminate the origin of defect. Furthermore, some post-treatment methods were also employed to alleviate the influence of the defect and to improve the laser damage resistance. Correction mask was introduced to improve the thickness uniformity, and the thickness uniformity can be amended to less than 1% in the range of Φ650 mm. Preliminary investigation related to surface deformation was also conducted.
文摘及时检测绝缘子自爆缺陷对输电线路安全可靠运行具有重要意义。针对深度学习模型对具有小目标特征的绝缘子自爆缺陷检测能力不足、模型结构复杂等问题,提出了一种基于轻量化改进YOLOv8n输电线路绝缘子自爆检测方法。以YOLOv8n网络为基础模型,通过添加小目标检测模块来捕捉绝缘子自爆的小目标细节信息,提高其检测能力;进一步,引入SIoU损失函数,解决原始CIoU损失函数未考虑真实框与预测框之间的方向问题,增强目标定位准确性;最后,使用通道剪枝方法,对改进模型进行剪枝,去除模型冗余参数、减少浮点运算量,降低模型计算成本和复杂度。在构建的绝缘子自爆数据集上的实验结果表明,轻量化改进方法的平均准确性均值达到97.1%,其浮点运算量和体积分别为4.9 G FLOPS和1.82 MB,仅为原始模型的60.5%和29.7%,合理兼顾了绝缘子自爆检测的准确性和模型复杂性。在另一个输电线路巡检数据集中,本研究方法对其他类型的小目标检测准确性也较好,具有良好的推广应用前景。
