Augmented solar images were used to research the adaptability of four representative image extraction and matching algorithms in space weather domain.These include the scale-invariant feature transform algorithm,speed...Augmented solar images were used to research the adaptability of four representative image extraction and matching algorithms in space weather domain.These include the scale-invariant feature transform algorithm,speeded-up robust features algorithm,binary robust invariant scalable keypoints algorithm,and oriented fast and rotated brief algorithm.The performance of these algorithms was estimated in terms of matching accuracy,feature point richness,and running time.The experiment result showed that no algorithm achieved high accuracy while keeping low running time,and all algorithms are not suitable for image feature extraction and matching of augmented solar images.To solve this problem,an improved method was proposed by using two-frame matching to utilize the accuracy advantage of the scale-invariant feature transform algorithm and the speed advantage of the oriented fast and rotated brief algorithm.Furthermore,our method and the four representative algorithms were applied to augmented solar images.Our application experiments proved that our method achieved a similar high recognition rate to the scale-invariant feature transform algorithm which is significantly higher than other algorithms.Our method also obtained a similar low running time to the oriented fast and rotated brief algorithm,which is significantly lower than other algorithms.展开更多
With the development of large scale text processing, the dimension of text feature space has become larger and larger, which has added a lot of difficulties to natural language processing. How to reduce the dimension...With the development of large scale text processing, the dimension of text feature space has become larger and larger, which has added a lot of difficulties to natural language processing. How to reduce the dimension has become a practical problem in the field. Here we present two clustering methods, i.e. concept association and concept abstract, to achieve the goal. The first refers to the keyword clustering based on the co occurrence of展开更多
The selective laser melting(SLM)processed aluminum alloys have already aroused researchers’attention in aerospace,rail transport and petrochemical engineering due to the comprehensive advantages of low density,good c...The selective laser melting(SLM)processed aluminum alloys have already aroused researchers’attention in aerospace,rail transport and petrochemical engineering due to the comprehensive advantages of low density,good corrosion resistance and high mechanical performance.In this paper,an Al-14.1Mg-0.47Si-0.31Sc-0.17Zr alloy was fabricated via SLM.The characteristics of single track at different process parameters,and the influence of hatch spacing on densification,microstructural features and tensile properties of block specimens were systematically studied.The hatch spacing has an influence on the overlap ratio of single track,and further affects the internal forming quality of printed specimen.At a laser power of 160 W and scanning speed of 400 mm/s,the densification of block specimen increased first and then decreased with the increase of hatch spacing.The nearly full dense specimen(98.7%)with a tensile strength of 452 MPa was fabricated at a hatch spacing of 80μm.Typical characteristics of dimple and cleavage on the tensile fracture of the AlMgSiScZr alloy showed the mixed fracture of ductility and brittleness.展开更多
煤矿井下弥漫着粉尘和雾气且多数区域为狭长巷道,仅依赖矿灯照明会导致视频监控图像出现细节模糊、局部过曝及目标尺寸多变等问题。这些因素增加了井下安全帽目标检测的难度,现有目标检测算法直接应用于煤矿井下场景时,通常面临精度不...煤矿井下弥漫着粉尘和雾气且多数区域为狭长巷道,仅依赖矿灯照明会导致视频监控图像出现细节模糊、局部过曝及目标尺寸多变等问题。这些因素增加了井下安全帽目标检测的难度,现有目标检测算法直接应用于煤矿井下场景时,通常面临精度不足的挑战。针对这些问题,研究提出一种基于YOLOv8n(You Only Look Once version 8n)的煤矿井下安全帽检测算法。首先,采用空间到深度机制将YOLOv8n主干网络中的Conv模块重新构建为空间到深度卷积(Space-to-Depth Convolutional,SPDConv)模块,以便从特征图中充分提取浅层细节信息,提高模型对细节模糊图像中小目标安全帽的检测精度;其次,引入基于注意力机制的尺度内特征交互模块,减少局部过曝对安全帽特征提取的干扰,增强模型对目标区域的关注能力;最后,借鉴高层次筛选特征融合金字塔对YOLOv8n的颈部网络进行重设计,改善模型对不同尺寸安全帽的检测能力,进一步提升检测精度。试验结果显示,该算法在CUMT-Helme T数据集上的平均精度均值达91.7%,相较于YOLOv8n提升了3.2百分点,同时模型参数量减少了1.9×10^(5)。与单次多边框检测(Single Shot MultiBox Detector,SSD)、快速区域卷积神经网络(Region-based Convolutional Neural Networks,Faster RCNN)、YOLOv5s、YOLOv6n、YOLOv7及YOLOv7-tiny等当前主流目标检测算法相比,该算法的平均精度均值最高,且参数量和浮点运算量较低,在实现较高检测精度的同时还具备一定的轻量化特性。展开更多
交通标志检测是自动驾驶系统、辅助驾驶系统(DAS)的重要组成部分,对行车安全具有重要意义。针对小目标交通标志检测时受光照、恶劣天气等因素影响而导致的检测精度低、漏检率高等问题,提出一种基于改进YOLOv5的小目标交通标志检测算法...交通标志检测是自动驾驶系统、辅助驾驶系统(DAS)的重要组成部分,对行车安全具有重要意义。针对小目标交通标志检测时受光照、恶劣天气等因素影响而导致的检测精度低、漏检率高等问题,提出一种基于改进YOLOv5的小目标交通标志检测算法。首先,引入空间到深度卷积(SPD-Conv)对特征图进行下采样,有效避免小目标信息丢失,提高小目标敏感度。其次,基于加权双向特征金字塔网络(BiFPN)改进颈部网络,添加跨层连接以融合多尺度特征。之后,增加小目标检测层,增强小目标检测能力。最后,采用SIoU(Shape-aware Intersection over Union)损失函数,关注真实框与预测框的角度信息。实验结果表明,改进后的算法在中国交通标志检测数据集(CCTSDB2021)上的平均精度均值(mAP)达到83.5%,相较于原YOLOv5提升了7.2个百分点,检测速度满足实时性要求。展开更多
基金Supported by the Key Research Program of the Chinese Academy of Sciences(ZDRE-KT-2021-3)。
文摘Augmented solar images were used to research the adaptability of four representative image extraction and matching algorithms in space weather domain.These include the scale-invariant feature transform algorithm,speeded-up robust features algorithm,binary robust invariant scalable keypoints algorithm,and oriented fast and rotated brief algorithm.The performance of these algorithms was estimated in terms of matching accuracy,feature point richness,and running time.The experiment result showed that no algorithm achieved high accuracy while keeping low running time,and all algorithms are not suitable for image feature extraction and matching of augmented solar images.To solve this problem,an improved method was proposed by using two-frame matching to utilize the accuracy advantage of the scale-invariant feature transform algorithm and the speed advantage of the oriented fast and rotated brief algorithm.Furthermore,our method and the four representative algorithms were applied to augmented solar images.Our application experiments proved that our method achieved a similar high recognition rate to the scale-invariant feature transform algorithm which is significantly higher than other algorithms.Our method also obtained a similar low running time to the oriented fast and rotated brief algorithm,which is significantly lower than other algorithms.
文摘With the development of large scale text processing, the dimension of text feature space has become larger and larger, which has added a lot of difficulties to natural language processing. How to reduce the dimension has become a practical problem in the field. Here we present two clustering methods, i.e. concept association and concept abstract, to achieve the goal. The first refers to the keyword clustering based on the co occurrence of
基金Project(51775481)supported by the National Natural Science Foundation of ChinaProject(E2019203418)supported by the Natural Science Foundation of Hebei Province,China。
文摘The selective laser melting(SLM)processed aluminum alloys have already aroused researchers’attention in aerospace,rail transport and petrochemical engineering due to the comprehensive advantages of low density,good corrosion resistance and high mechanical performance.In this paper,an Al-14.1Mg-0.47Si-0.31Sc-0.17Zr alloy was fabricated via SLM.The characteristics of single track at different process parameters,and the influence of hatch spacing on densification,microstructural features and tensile properties of block specimens were systematically studied.The hatch spacing has an influence on the overlap ratio of single track,and further affects the internal forming quality of printed specimen.At a laser power of 160 W and scanning speed of 400 mm/s,the densification of block specimen increased first and then decreased with the increase of hatch spacing.The nearly full dense specimen(98.7%)with a tensile strength of 452 MPa was fabricated at a hatch spacing of 80μm.Typical characteristics of dimple and cleavage on the tensile fracture of the AlMgSiScZr alloy showed the mixed fracture of ductility and brittleness.
文摘煤矿井下弥漫着粉尘和雾气且多数区域为狭长巷道,仅依赖矿灯照明会导致视频监控图像出现细节模糊、局部过曝及目标尺寸多变等问题。这些因素增加了井下安全帽目标检测的难度,现有目标检测算法直接应用于煤矿井下场景时,通常面临精度不足的挑战。针对这些问题,研究提出一种基于YOLOv8n(You Only Look Once version 8n)的煤矿井下安全帽检测算法。首先,采用空间到深度机制将YOLOv8n主干网络中的Conv模块重新构建为空间到深度卷积(Space-to-Depth Convolutional,SPDConv)模块,以便从特征图中充分提取浅层细节信息,提高模型对细节模糊图像中小目标安全帽的检测精度;其次,引入基于注意力机制的尺度内特征交互模块,减少局部过曝对安全帽特征提取的干扰,增强模型对目标区域的关注能力;最后,借鉴高层次筛选特征融合金字塔对YOLOv8n的颈部网络进行重设计,改善模型对不同尺寸安全帽的检测能力,进一步提升检测精度。试验结果显示,该算法在CUMT-Helme T数据集上的平均精度均值达91.7%,相较于YOLOv8n提升了3.2百分点,同时模型参数量减少了1.9×10^(5)。与单次多边框检测(Single Shot MultiBox Detector,SSD)、快速区域卷积神经网络(Region-based Convolutional Neural Networks,Faster RCNN)、YOLOv5s、YOLOv6n、YOLOv7及YOLOv7-tiny等当前主流目标检测算法相比,该算法的平均精度均值最高,且参数量和浮点运算量较低,在实现较高检测精度的同时还具备一定的轻量化特性。
文摘交通标志检测是自动驾驶系统、辅助驾驶系统(DAS)的重要组成部分,对行车安全具有重要意义。针对小目标交通标志检测时受光照、恶劣天气等因素影响而导致的检测精度低、漏检率高等问题,提出一种基于改进YOLOv5的小目标交通标志检测算法。首先,引入空间到深度卷积(SPD-Conv)对特征图进行下采样,有效避免小目标信息丢失,提高小目标敏感度。其次,基于加权双向特征金字塔网络(BiFPN)改进颈部网络,添加跨层连接以融合多尺度特征。之后,增加小目标检测层,增强小目标检测能力。最后,采用SIoU(Shape-aware Intersection over Union)损失函数,关注真实框与预测框的角度信息。实验结果表明,改进后的算法在中国交通标志检测数据集(CCTSDB2021)上的平均精度均值(mAP)达到83.5%,相较于原YOLOv5提升了7.2个百分点,检测速度满足实时性要求。
