A 3D laser scanning strategy based on cascaded deep neural network is proposed for the scanning system converted from 2D Lidar with a pitching motion device. The strategy is aimed at moving target detection and monito...A 3D laser scanning strategy based on cascaded deep neural network is proposed for the scanning system converted from 2D Lidar with a pitching motion device. The strategy is aimed at moving target detection and monitoring. Combining the device characteristics, the strategy first proposes a cascaded deep neural network, which inputs 2D point cloud, color image and pitching angle. The outputs are target distance and speed classification. And the cross-entropy loss function of network is modified by using focal loss and uniform distribution to improve the recognition accuracy. Then a pitching range and speed model are proposed to determine pitching motion parameters. Finally, the adaptive scanning is realized by integral separate speed PID. The experimental results show that the accuracies of the improved network target detection box, distance and speed classification are 90.17%, 96.87% and 96.97%, respectively. The average speed error of the improved PID is 0.4239°/s, and the average strategy execution time is 0.1521 s.The range and speed model can effectively reduce the collection of useless information and the deformation of the target point cloud. Conclusively, the experimental of overall scanning strategy show that it can improve target point cloud integrity and density while ensuring the capture of target.展开更多
In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particul...In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.展开更多
[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore ...[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.展开更多
Cutting off or controlling the enemy’s power supply at critical moments or strategic locations may result in a cascade failure,thus gaining an advantage in a war.However,the exist-ing cascading failure modeling analy...Cutting off or controlling the enemy’s power supply at critical moments or strategic locations may result in a cascade failure,thus gaining an advantage in a war.However,the exist-ing cascading failure modeling analysis of interdependent net-works is insufficient for describing the load characteristics and dependencies of subnetworks,and it is difficult to use for model-ing and failure analysis of power-combat(P-C)coupling net-works.This paper considers the physical characteristics of the two subnetworks and studies the mechanism of fault propaga-tion between subnetworks and across systems.Then the surviv-ability of the coupled network is evaluated.Firstly,an integrated modeling approach for the combat system and power system is predicted based on interdependent network theory.A heteroge-neous one-way interdependent network model based on proba-bility dependence is constructed.Secondly,using the operation loop theory,a load-capacity model based on combat-loop betweenness is proposed,and the cascade failure model of the P-C coupling system is investigated from three perspectives:ini-tial capacity,allocation strategy,and failure mechanism.Thirdly,survivability indexes based on load loss rate and network sur-vival rate are proposed.Finally,the P-C coupling system is con-structed based on the IEEE 118-bus system to demonstrate the proposed method.展开更多
单位种植面积的麦穗数量是评估小麦产量的关键农艺指标之一。针对农田复杂场景中存在的大量麦芒、卷曲麦叶、杂草等环境噪声、小尺寸目标和光照不均等导致的麦穗检测准确度下降的问题,提出了一种基于深度学习的麦穗检测方法(FCS RCNN)。...单位种植面积的麦穗数量是评估小麦产量的关键农艺指标之一。针对农田复杂场景中存在的大量麦芒、卷曲麦叶、杂草等环境噪声、小尺寸目标和光照不均等导致的麦穗检测准确度下降的问题,提出了一种基于深度学习的麦穗检测方法(FCS RCNN)。以Cascade RCNN为基本网络模型,通过引入特征金字塔网络(Feature pyramid network,FPN)融合浅层细节特征和高层丰富语义特征,通过采用在线难例挖掘(Online hard example mining,OHEM)技术增加对高损失样本的训练频次,通过IOU(Intersection over union)阈值对网络模型进行阶段性融合,最后基于圆形LBP纹理特征训练一个SVM分类器,对麦穗检出结果进行复验。大田图像测试表明,FCS RCNN模型的检测精度达92.9%,识别单幅图像平均耗时为0.357 s,平均精度为81.22%,比Cascade RCNN提高了21.76个百分点。展开更多
针对光照不均、噪声大、拍摄质量不高的夜晚水下环境,为实现夜晚水下图像中鱼类目标的快速检测,利用计算机视觉技术,提出了一种基于改进Cascade R-CNN算法和具有色彩保护的MSRCP(Multi-scale Retinex with color restoration)图像增强...针对光照不均、噪声大、拍摄质量不高的夜晚水下环境,为实现夜晚水下图像中鱼类目标的快速检测,利用计算机视觉技术,提出了一种基于改进Cascade R-CNN算法和具有色彩保护的MSRCP(Multi-scale Retinex with color restoration)图像增强算法的夜晚水下鱼类目标检测方法。首先针对夜晚水下环境的视频数据,根据时间间隔,截取出相应的夜晚水下鱼类图像,对截取的原始图像进行MSRCP图像增强。然后采用DetNASNet主干网络进行网络训练和水下鱼类特征信息的提取,将提取出的特征信息输入到Cascade R-CNN模型中,并使用Soft-NMS候选框优化算法对其中的RPN网络进行优化,最后对夜晚水下鱼类目标进行检测。实验结果表明,该方法解决了夜晚水下环境中的图像降质、鱼类目标重叠检测问题,实现了对夜晚水下鱼类目标的快速检测,对夜晚水下鱼类图像目标检测的查准率达到95.81%,比Cascade R-CNN方法提高了11.57个百分点。展开更多
基金funded by National Natural Science Foundation of China(Grant No. 51805146)the Fundamental Research Funds for the Central Universities (Grant No. B200202221)+1 种基金Jiangsu Key R&D Program (Grant Nos. BE2018004-1, BE2018004)College Students’ Innovative Entrepreneurial Training Plan Program (Grant No. 2020102941513)。
文摘A 3D laser scanning strategy based on cascaded deep neural network is proposed for the scanning system converted from 2D Lidar with a pitching motion device. The strategy is aimed at moving target detection and monitoring. Combining the device characteristics, the strategy first proposes a cascaded deep neural network, which inputs 2D point cloud, color image and pitching angle. The outputs are target distance and speed classification. And the cross-entropy loss function of network is modified by using focal loss and uniform distribution to improve the recognition accuracy. Then a pitching range and speed model are proposed to determine pitching motion parameters. Finally, the adaptive scanning is realized by integral separate speed PID. The experimental results show that the accuracies of the improved network target detection box, distance and speed classification are 90.17%, 96.87% and 96.97%, respectively. The average speed error of the improved PID is 0.4239°/s, and the average strategy execution time is 0.1521 s.The range and speed model can effectively reduce the collection of useless information and the deformation of the target point cloud. Conclusively, the experimental of overall scanning strategy show that it can improve target point cloud integrity and density while ensuring the capture of target.
基金Supported by the National Natural Science Foundation of China(62105039)。
文摘In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.
文摘[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river.
基金supported by the National Natural Science Foundation of China(72271242)Hunan Provincial Natural Science Foundation of China for Excellent Young Scholars(2022JJ20046).
文摘Cutting off or controlling the enemy’s power supply at critical moments or strategic locations may result in a cascade failure,thus gaining an advantage in a war.However,the exist-ing cascading failure modeling analysis of interdependent net-works is insufficient for describing the load characteristics and dependencies of subnetworks,and it is difficult to use for model-ing and failure analysis of power-combat(P-C)coupling net-works.This paper considers the physical characteristics of the two subnetworks and studies the mechanism of fault propaga-tion between subnetworks and across systems.Then the surviv-ability of the coupled network is evaluated.Firstly,an integrated modeling approach for the combat system and power system is predicted based on interdependent network theory.A heteroge-neous one-way interdependent network model based on proba-bility dependence is constructed.Secondly,using the operation loop theory,a load-capacity model based on combat-loop betweenness is proposed,and the cascade failure model of the P-C coupling system is investigated from three perspectives:ini-tial capacity,allocation strategy,and failure mechanism.Thirdly,survivability indexes based on load loss rate and network sur-vival rate are proposed.Finally,the P-C coupling system is con-structed based on the IEEE 118-bus system to demonstrate the proposed method.
文摘单位种植面积的麦穗数量是评估小麦产量的关键农艺指标之一。针对农田复杂场景中存在的大量麦芒、卷曲麦叶、杂草等环境噪声、小尺寸目标和光照不均等导致的麦穗检测准确度下降的问题,提出了一种基于深度学习的麦穗检测方法(FCS RCNN)。以Cascade RCNN为基本网络模型,通过引入特征金字塔网络(Feature pyramid network,FPN)融合浅层细节特征和高层丰富语义特征,通过采用在线难例挖掘(Online hard example mining,OHEM)技术增加对高损失样本的训练频次,通过IOU(Intersection over union)阈值对网络模型进行阶段性融合,最后基于圆形LBP纹理特征训练一个SVM分类器,对麦穗检出结果进行复验。大田图像测试表明,FCS RCNN模型的检测精度达92.9%,识别单幅图像平均耗时为0.357 s,平均精度为81.22%,比Cascade RCNN提高了21.76个百分点。
文摘针对光照不均、噪声大、拍摄质量不高的夜晚水下环境,为实现夜晚水下图像中鱼类目标的快速检测,利用计算机视觉技术,提出了一种基于改进Cascade R-CNN算法和具有色彩保护的MSRCP(Multi-scale Retinex with color restoration)图像增强算法的夜晚水下鱼类目标检测方法。首先针对夜晚水下环境的视频数据,根据时间间隔,截取出相应的夜晚水下鱼类图像,对截取的原始图像进行MSRCP图像增强。然后采用DetNASNet主干网络进行网络训练和水下鱼类特征信息的提取,将提取出的特征信息输入到Cascade R-CNN模型中,并使用Soft-NMS候选框优化算法对其中的RPN网络进行优化,最后对夜晚水下鱼类目标进行检测。实验结果表明,该方法解决了夜晚水下环境中的图像降质、鱼类目标重叠检测问题,实现了对夜晚水下鱼类目标的快速检测,对夜晚水下鱼类图像目标检测的查准率达到95.81%,比Cascade R-CNN方法提高了11.57个百分点。
