A high-energy 100-Hz optical parametric oscillator(OPO)based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated.A KTA-based OPO with a good beam quality was obtained when the magnifi...A high-energy 100-Hz optical parametric oscillator(OPO)based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated.A KTA-based OPO with a good beam quality was obtained when the magnification factor was 1.5,corresponding to the maximum signal(1.53μm)energy of 56 m J and idler(3.47μm)energy of 20 m J,respectively.The beam quality factors(M^(2))were measured to be M^(2)_(x)=5.7,M^(2)_(y)=5.9 for signal and M^(2)_(x)=8.4,M^(2)_(y)=8.1 for idler accordingly.The experimental results indicated that the beam quality positively changed with the increase of magnification factors,accompanied by an acceptable loss of pulse energy.展开更多
Some sharp upper bounds of Laplacian spectral radius of trees in terms of order,diameter,pendant vertex number,covering number,edge covering number or total independence number are given.And the ninth to thirteenth la...Some sharp upper bounds of Laplacian spectral radius of trees in terms of order,diameter,pendant vertex number,covering number,edge covering number or total independence number are given.And the ninth to thirteenth largest values of Laplacian spectral radius over the class of trees on a given order are also given.展开更多
Let （V, U） be the vertex-partition of tree T as a bipartite graph. T is called an （m, n）-tree if ｜V｜ = m and ｜U｜ = n. For given positive integers m, n and d, the maximum spectral radius of all （m, n）-trees o...Let （V, U） be the vertex-partition of tree T as a bipartite graph. T is called an （m, n）-tree if ｜V｜ = m and ｜U｜ = n. For given positive integers m, n and d, the maximum spectral radius of all （m, n）-trees on diameter d are obtained, and all extreme graphs are determined.展开更多
安全帽作为作业工人最基本的个体防护装备,对作业人员的生命安全具有重要意义.但是部分作业人员安全意识缺乏,不佩戴安全帽行为时常发生.本文聚焦于复杂场景下对工作人员是否佩戴安全帽的实时检测.YOLO(You Only Look Once)是当前最为...安全帽作为作业工人最基本的个体防护装备,对作业人员的生命安全具有重要意义.但是部分作业人员安全意识缺乏,不佩戴安全帽行为时常发生.本文聚焦于复杂场景下对工作人员是否佩戴安全帽的实时检测.YOLO(You Only Look Once)是当前最为先进的实时目标检测算法,在检测精度和速度上都取得了良好的效果,将YOLO应用于安全帽检测.针对未佩戴安全帽单类检测问题,修改分类器,将输出修改为18维度的张量.基于YOLOv3在ImageNet上的预训练模型,对实际场景下采集到的2010张样本进行标注并训练,根据损失函数和IOU曲线对模型进行优化调参,最终得到最优的安全帽检测模型.实验结果表明,在2000张图片测试集上取得了98.7%的准确率,在无GPU环境下平均检测速度达到了35 fps,满足实时性的检测要求,验证了基于YOLOv3安全帽检测方法的有效性.展开更多
郊狼优化算法(Coyote optimization algorithm,COA)是最近提出的一种新颖且具有较大应用潜力的群智能优化算法,具有独特的搜索机制和能较好解决全局优化问题等优势,但在处理复杂优化问题时存在搜索效率低、可操作性差和收敛速度慢等不足...郊狼优化算法(Coyote optimization algorithm,COA)是最近提出的一种新颖且具有较大应用潜力的群智能优化算法,具有独特的搜索机制和能较好解决全局优化问题等优势,但在处理复杂优化问题时存在搜索效率低、可操作性差和收敛速度慢等不足.为弥补其不足,并借鉴灰狼优化算法(Grey wolf optimizer,GWO)的优势,提出了一种COA与GWO的混合算法(Hybrid COA with GWO,HCOAG).首先提出了一种改进的COA(Improved COA,ICOA),即将一种高斯全局趋优成长算子替换原算法的成长算子以提高搜索效率和收敛速度,并提出一种动态调整组内郊狼数方案,使得算法的搜索能力和可操作性都得到增强;然后提出了一种简化操作的GWO(Simplified GWO,SGWO),以提高算法的可操作性和降低其计算复杂度;最后采用正弦交叉策略将ICOA与SGWO二者融合,进一步获得更好的优化性能.大量的经典函数和CEC2017复杂函数优化以及K-Means聚类优化的实验结果表明,与COA相比,HCOAG具有更高的搜索效率、更强的可操作性和更快的收敛速度,与其他先进的对比算法相比,HCOAG具有更好的优化性能,能更好地解决聚类优化问题.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62075116 and 62075117)Key Research Program of Shandong Province(No.2020JMRH0302)+2 种基金Natural Science Foundation of Shandong Province(Nos.ZR2019MF039,ZR2020MF114,and ZR2022QF087)Founding for Qilu Young Scholars from Shandong UniversityChina Postdoctoral Science Foundation(No.2021TQ0190)。
文摘A high-energy 100-Hz optical parametric oscillator(OPO)based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated.A KTA-based OPO with a good beam quality was obtained when the magnification factor was 1.5,corresponding to the maximum signal(1.53μm)energy of 56 m J and idler(3.47μm)energy of 20 m J,respectively.The beam quality factors(M^(2))were measured to be M^(2)_(x)=5.7,M^(2)_(y)=5.9 for signal and M^(2)_(x)=8.4,M^(2)_(y)=8.1 for idler accordingly.The experimental results indicated that the beam quality positively changed with the increase of magnification factors,accompanied by an acceptable loss of pulse energy.
基金Supported by National Natural Science Foundation of China（10871204）
文摘Some sharp upper bounds of Laplacian spectral radius of trees in terms of order,diameter,pendant vertex number,covering number,edge covering number or total independence number are given.And the ninth to thirteenth largest values of Laplacian spectral radius over the class of trees on a given order are also given.
基金Supported by the Department Fund of Science and Technology in Tianjin Higher Education Institutions(20050404)
文摘Let （V, U） be the vertex-partition of tree T as a bipartite graph. T is called an （m, n）-tree if ｜V｜ = m and ｜U｜ = n. For given positive integers m, n and d, the maximum spectral radius of all （m, n）-trees on diameter d are obtained, and all extreme graphs are determined.
文摘安全帽作为作业工人最基本的个体防护装备,对作业人员的生命安全具有重要意义.但是部分作业人员安全意识缺乏,不佩戴安全帽行为时常发生.本文聚焦于复杂场景下对工作人员是否佩戴安全帽的实时检测.YOLO(You Only Look Once)是当前最为先进的实时目标检测算法,在检测精度和速度上都取得了良好的效果,将YOLO应用于安全帽检测.针对未佩戴安全帽单类检测问题,修改分类器,将输出修改为18维度的张量.基于YOLOv3在ImageNet上的预训练模型,对实际场景下采集到的2010张样本进行标注并训练,根据损失函数和IOU曲线对模型进行优化调参,最终得到最优的安全帽检测模型.实验结果表明,在2000张图片测试集上取得了98.7%的准确率,在无GPU环境下平均检测速度达到了35 fps,满足实时性的检测要求,验证了基于YOLOv3安全帽检测方法的有效性.
文摘郊狼优化算法(Coyote optimization algorithm,COA)是最近提出的一种新颖且具有较大应用潜力的群智能优化算法,具有独特的搜索机制和能较好解决全局优化问题等优势,但在处理复杂优化问题时存在搜索效率低、可操作性差和收敛速度慢等不足.为弥补其不足,并借鉴灰狼优化算法(Grey wolf optimizer,GWO)的优势,提出了一种COA与GWO的混合算法(Hybrid COA with GWO,HCOAG).首先提出了一种改进的COA(Improved COA,ICOA),即将一种高斯全局趋优成长算子替换原算法的成长算子以提高搜索效率和收敛速度,并提出一种动态调整组内郊狼数方案,使得算法的搜索能力和可操作性都得到增强;然后提出了一种简化操作的GWO(Simplified GWO,SGWO),以提高算法的可操作性和降低其计算复杂度;最后采用正弦交叉策略将ICOA与SGWO二者融合,进一步获得更好的优化性能.大量的经典函数和CEC2017复杂函数优化以及K-Means聚类优化的实验结果表明,与COA相比,HCOAG具有更高的搜索效率、更强的可操作性和更快的收敛速度,与其他先进的对比算法相比,HCOAG具有更好的优化性能,能更好地解决聚类优化问题.
