针对传统图像识别算法匹配正确率低、运行时间较长等问题,文中提出了基于改进ORB-FLANN(Oriented FAST and Rotated BRIEF-Fast Library for Approximate Nearest Neighbors)的工件图像识别方法。对ORB算法特征描述、图像特征匹配算法...针对传统图像识别算法匹配正确率低、运行时间较长等问题,文中提出了基于改进ORB-FLANN(Oriented FAST and Rotated BRIEF-Fast Library for Approximate Nearest Neighbors)的工件图像识别方法。对ORB算法特征描述、图像特征匹配算法进行修改,解决传统图像识别算法在图像存在尺度和旋转变换情况下存在的弊端并降低误匹配率。该方法对ORB算法检测到的特征点采用SURF(Speeded Up Robust Features)算法添加方向信息并完成特征描述,得到旋转尺度不变性的特征点,结合FLANN算法并引入双向匹配策略进行特征点粗匹配,最后利用渐进采样一致算法进一步剔除误匹配点对完成精匹配。实验结果表明,与其他方法相比,改进算法在处理尺度、旋转等变换图像时,匹配正确率分别提高了2.6%~18.8%和29.5%~43.9%,运行时长均在4 s以内,提高了对工件图像的识别效率和精准性。展开更多
采用干燥空气取代SF_(6)绝缘的中压充气柜,符合绿色环保发展方向,但空气的对流散热能力弱于SF_(6),这对充气柜的散热结构提出了更高要求。文中提出了一种采用纵向直线布置主回路的40.5 k V 2 500 A干燥空气绝缘充气柜总体结构,其具有主...采用干燥空气取代SF_(6)绝缘的中压充气柜,符合绿色环保发展方向,但空气的对流散热能力弱于SF_(6),这对充气柜的散热结构提出了更高要求。文中提出了一种采用纵向直线布置主回路的40.5 k V 2 500 A干燥空气绝缘充气柜总体结构,其具有主导电回路短、发热功率较低的特点。对该充气柜进行发热与散热分析、仿真和试验研究,发现采用常规结构气箱时,其内部空气温升达60 K左右,气箱内热量无法散到气箱外部是整体温升超标的主要因素。从增强对流散热和辐射散热方面对散热结构进行优化,重点设计了柜体侧板外表面的散热通道,优化后的方案通过了1.1×2 500 A温升试验,验证了设计和优化思路的可行性。展开更多
A novel differential quasi-Yagi antenna is first presented and compared with a normal single-ended counterpart.The simulated and measured results show that the differential quasi-Yagi antenna outperforms the conventio...A novel differential quasi-Yagi antenna is first presented and compared with a normal single-ended counterpart.The simulated and measured results show that the differential quasi-Yagi antenna outperforms the conventional single-ended one.The differential quasi-Yagi antenna is then used as an element for linear arrays.A study of the coupling mechanism between the two differential and the two singleended quasi-Yagi antennas is conducted,which reveals that the TE0 mode is the dominant mode,and the driver is the decisive part to account for the mutual coupling.Next,the effects of four decoupling structures are respectively evaluated between the two differential quasi-Yagi antennas.Finally,the arrays with simple but effective decoupling structures are fabricated and measured.The measured results demonstrate that the simple slit or air-hole decoupling structure can reduce the coupling level from−18 dB to−25 dB and meanwhile maintain the impedance matching and radiation patterns of the array over the broad bandwidth.The differential quasi-Yagi antenna should be a promising antenna candidate for many applications.展开更多
文摘针对传统图像识别算法匹配正确率低、运行时间较长等问题,文中提出了基于改进ORB-FLANN(Oriented FAST and Rotated BRIEF-Fast Library for Approximate Nearest Neighbors)的工件图像识别方法。对ORB算法特征描述、图像特征匹配算法进行修改,解决传统图像识别算法在图像存在尺度和旋转变换情况下存在的弊端并降低误匹配率。该方法对ORB算法检测到的特征点采用SURF(Speeded Up Robust Features)算法添加方向信息并完成特征描述,得到旋转尺度不变性的特征点,结合FLANN算法并引入双向匹配策略进行特征点粗匹配,最后利用渐进采样一致算法进一步剔除误匹配点对完成精匹配。实验结果表明,与其他方法相比,改进算法在处理尺度、旋转等变换图像时,匹配正确率分别提高了2.6%~18.8%和29.5%~43.9%,运行时长均在4 s以内,提高了对工件图像的识别效率和精准性。
文摘采用干燥空气取代SF_(6)绝缘的中压充气柜,符合绿色环保发展方向,但空气的对流散热能力弱于SF_(6),这对充气柜的散热结构提出了更高要求。文中提出了一种采用纵向直线布置主回路的40.5 k V 2 500 A干燥空气绝缘充气柜总体结构,其具有主导电回路短、发热功率较低的特点。对该充气柜进行发热与散热分析、仿真和试验研究,发现采用常规结构气箱时,其内部空气温升达60 K左右,气箱内热量无法散到气箱外部是整体温升超标的主要因素。从增强对流散热和辐射散热方面对散热结构进行优化,重点设计了柜体侧板外表面的散热通道,优化后的方案通过了1.1×2 500 A温升试验,验证了设计和优化思路的可行性。
文摘A novel differential quasi-Yagi antenna is first presented and compared with a normal single-ended counterpart.The simulated and measured results show that the differential quasi-Yagi antenna outperforms the conventional single-ended one.The differential quasi-Yagi antenna is then used as an element for linear arrays.A study of the coupling mechanism between the two differential and the two singleended quasi-Yagi antennas is conducted,which reveals that the TE0 mode is the dominant mode,and the driver is the decisive part to account for the mutual coupling.Next,the effects of four decoupling structures are respectively evaluated between the two differential quasi-Yagi antennas.Finally,the arrays with simple but effective decoupling structures are fabricated and measured.The measured results demonstrate that the simple slit or air-hole decoupling structure can reduce the coupling level from−18 dB to−25 dB and meanwhile maintain the impedance matching and radiation patterns of the array over the broad bandwidth.The differential quasi-Yagi antenna should be a promising antenna candidate for many applications.
