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Electrically-driven ultrafast out-of-equilibrium light emission from hot electrons in suspended graphene/hBN heterostructures

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International Journal of Extreme Manufacturing 2024年第1期6卷 328-338页

作者： Qiang Liu w.i Xu Xiaoxi Li Tongyao Zhang Chengbing Qin Fang Luo Zhihong Zhu shiqiao Qin Mengjian Zhu Kostya s Novoselov College of Advanced Interdisciplinary studies&Hunan Provincial Key Laboratory of Novel Nano-optoelectronic Information Materials and Devices National University of Defense TechnologyChangshaHunan 410073People’s Republic of China Nanhu Laser Laboratory National University of Defense TechnologyChangshaHunan 410073People’s Republic of China state Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006People’s Republic of China Collaborative Innovation center of Extreme Optics Shanxi UniversityTaiyuan 030006People’s Republic of China state Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyShanxi UniversityTaiyuan 030006People’s Republic of China Institute for Functional Intelligent Materials National University of SingaporeSingapore 117544Singapore Department of Materials science and Engineering National University of SingaporeSingapore 117575Singapore

Nanoscale light sources w.th high speed of electrical modulation and low.energy consumption are key components for nanophotonics and *** record-high carrier mobility and ultrafast carrier dynamics of graphene make it promising as an atomically thin light emitter w.ich can be further integrated into arbitrary platforms by van der w.als ***,due to the zero bandgap,graphene is difficult to emit light through the interband recombination of carriers like conventional ***,w. demonstrate ultrafast thermal light emitters based on suspended graphene/hexagonal boron nitride(gr/hBN)*** in biased graphene are significantly heated up to 2800 K at modest electric fields,emitting bright photons from the near-infrared to the visible spectral *** eliminating the heat dissipation channel of the substrate,the radiation efficiency of the suspended gr/hBN device is about tw. orders of magnitude greater than that of graphene devices supported on siO2or *** demonstrate that hot electrons and low.energy acoustic phonons in graphene are w.akly coupled to each other and are not in full thermal *** cooling ofhigh-temperature hot electrons to low.temperature acoustic phonons is enabled by the significant near-field heat transfer at the highly localized gr/hBN interface,resulting in ultrafast thermal emission w.th up to 1 GHz bandw.dth under electrical *** is found thatsuspending the gr/hBN heterostructures on the siO2trenches significantly modifies the light emission due to the formation of the optical cavity and show.d a~440%enhancement inintensity at the peak w.velength of 940 nm compared to the black-body thermal *** demonstration of electrically driven ultrafast light emission from suspended gr/hBNheterostructures sheds the light on applications of graphene heterostructures in photonicintegrated circuits,such as broadband light sources and ultrafast thermo-optic phase modulat

关键词： suspended graphene ultrafast light emitter van der w.als heterostructures thermal radiation electron–phonon interaction

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旋转对置活塞发动机运动学特性研究

北京理工大学学报 2024年第4期44卷 369-376页

作者：王余枫高建兵赵玉伟黄俊峰宋纪龙付忠惠杨策北京理工大学机械与车辆学院北京100081 空军工程大学防空反导学院陕西西安710051

高功率密度发动机是未来内燃机的发展趋势.旋转对置活塞发动机结构简单,做功频率是传统往复式活塞发动机的两倍,可以显著提高发动机的理论功率密度,是小型无人机、混合动力系统的理想动力源.文中通过建立数学模型,探究了旋转对置活塞发... 详细信息

高功率密度发动机是未来内燃机的发展趋势.旋转对置活塞发动机结构简单,做功频率是传统往复式活塞发动机的两倍,可以显著提高发动机的理论功率密度,是小型无人机、混合动力系统的理想动力源.文中通过建立数学模型,探究了旋转对置活塞发动机的结构参数对活塞运动规律、气缸容积变化规律和压缩比的影响,分析了相邻活塞运动碰撞的边界条件.研究结果表明,活塞线速度对椭圆齿轮节曲线偏心率的变化最为敏感,当线速度大于平均值时,线速度与偏心率成正比,线速度小于平均值时则成反比;偏心率的增大可以减小气缸的余隙容积,且使下止点对应的气缸容积增大,进而调节发动机的压缩比;活塞端面夹角增大可以减小气缸的余隙容积;偏心率和活塞端面夹角在±10%的范围内变化时,压缩比相应的变化范围分别为5.62~12.04和5.01~23.45,当偏心率过大时将导致相邻活塞发生碰撞.

关键词：旋转对置活塞发动机椭圆齿轮副结构参数运动规律压缩比

stochastic stabilization of Markovian jump cloud control systems based on max-plus algebra

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Journal of systems Engineering and Electronics 2022年第4期33卷 827-834页

作者： w.NG Jin YANG Hongjiu XIA Yuanqing YAN ce school of Electrical and Information Engineering Tianjin UniversityTianjin 300072China school of Automation Beijing Institute of TechnologyBeijing 100081China

In this paper, stochastic stabilization is investigated by max-plus algebra for a Markovian jump cloud control system w.th a reference signal. For the Markovian jump cloud control system, there exists framew.rk adjustment w.ose evolution is satisfied w.th a Markov chain. Using max-plus algebra, a maxplus stochastic system is used to describe the Markovian jump cloud control system. A causal feedback matrix is obtained by exponential stability analysis for a causal feedback controller of the Markovian jump cloud control system. A sufficient condition is given to ensure existence on the causal feedback matrix of the causal feedback controller. Based on the causal feedback controller, stochastic stabilization in probability is analyzed for the Markovian jump cloud control system w.th a reference *** results are given to show.effectiveness of the causal feedback controller for the Markovian jump cloud control system.

关键词： Markovian jump cloud control system causal feedback controller max-plus algebra max-product algebra stochastic stabilization

Dynamic scaling of surface grow.h in the Influence of small Clusters Mobility

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Chinese Physics Letters 2000年第4期17卷 285-287页

作者： ZHUANG Guo-ce w.NG w.i National Laboratory of solid state Microstructure and Department of Physics Nanjing UniversityNanjing 210093 Department of Physics Yancheng Teacher's CollegeJiangsu 224002

The deposition,diffusion and coalescence processes appeared in the surface grow.h of compact or liquid-like clusters system are *** introducing a critical cluster size ic,such that clusters of size s≤ic are mobile w.ile clusters of the size s>ic are immobile,the effects of mobility of small clusters on cluster size distribution are *** ic increases,the exponentγw.ich relates the maximum cluster density to the normalized deposition rate is *** simudation results indicate that the scaled cluster-size distributions are independent of the deposition rate,but closely associated w.th the small clusters *** ic increases,it is found that the distributions become narrow.

关键词： cluster narrow normalized

In-flight Energy Calibration of the GECAM Gamma-ray Detectors

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Research in Astronomy and Astrophysics 2024年第10期24卷 48-57页

作者： Rui Qiao Dong-Ya Guo w.n-Xi Peng Yan-Qiu Zhang shuo Xiao shao-Lin Xiong Chao Zheng Chao-Yang Li Jia-Cong Liu w.ng-Chen Xue Jian-Jian He Zheng-Hua An Da-Li Zhang Xin-Qiao Li Li-Ming song shi-Jie Zheng Ke Gong Ya-Qing Liu Xin-Ying song Xiao-Yun Zhao Xiang-Yang w.n Yan-Bing Xu Xiang Ma Xiao-Bo Li Ping w.ng Yue Huang ce Cai Qi-Bin Yi Yi Zhao Chen-w.i w.ng Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of sciences Beijing 100049China China w.st Normal University Nanchong 637002China Xiangtan University Xiangtan 411105China Beijing Normal University Beijing 100875China

The gravitational w.ve high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(grBs)associated w.th gravitational w.ves and other high-energy transient *** mission consists of tw. microsatellites w.ich are planned to operate at the opposite sides of the *** GECAM satellite could detect and localize grBs in about 8 keV-5 MeV w.th its 25 Gamma-Ray Detectors(grDs).In this w.rk,w. report the in-flight energy calibration of grDs using the characteristic gamma-ray lines in the background spectra,and show.their performance evolution during the commissioning ***,a preliminary cross-calibration of energy response w.th Fermi GBM data is also presented,validating the energy response of grDs.

关键词： (stars:)gamma-ray burst:general instrumentation:detectors methods:data analysis

基于博弈理论组合权重的工业机器人可靠性指标分配研究

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机械设计 2024年第5期41卷 144-152页

作者：白斌周策曾省忠李林周枫林湖南第一师范学院智能制造学院湖南长沙410205 河北工业大学机械工程学院天津300401

针对工业机器人可靠性指标分配存在认知不确定性问题,文中提出了一种基于博弈理论组合权重的工业机器人可靠性指标评估方法。该方法考虑有效数据资料不完整和主观影响因素的不确定性,结合犹豫模糊集与灰色关联理论,将工业机器人影响较... 详细信息

针对工业机器人可靠性指标分配存在认知不确定性问题,文中提出了一种基于博弈理论组合权重的工业机器人可靠性指标评估方法。该方法考虑有效数据资料不完整和主观影响因素的不确定性,结合犹豫模糊集与灰色关联理论,将工业机器人影响较大的因素进行细化分析,建立了二层影响因素分配数学模型。首先,分析了一层影响因素之间的关联性,避免了由于独立考虑各指标给计算结果带来偏差;在此基础上引入基于离散正态分布的有序加权(Ow.)评价法,避免了个别决策者不公正或者评价不准确的主观因素对决策结果造成的负面影响;最后,采用博弈论的组合赋权思想计算出分配的综合权重,进行可靠性分配,为工业机器人的设计及可靠性评估提供参考依据。

关键词：工业机器人可靠性分配多层综合因子分配方法灰色关联 Ow. 博弈理论

基于视觉注意机制分析的疏散照明设计方法研究

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照明工程学报 2024年第3期35卷 82-88页

作者：郑策张明宇常瑜天津商业大学天津300134 天津大学天津300072

为改善城市夜间突发情况的人流疏散问题,本文将人的视觉注意机制融入到景观疏散照明设计过程中,基于人的视觉注意力分析,形成了景观疏散照明设计分析方法。在具体的设计流程中,导入TRIZ理论的“物质-场与标准解”问题分析与求解工具,将... 详细信息

为改善城市夜间突发情况的人流疏散问题,本文将人的视觉注意机制融入到景观疏散照明设计过程中,基于人的视觉注意力分析,形成了景观疏散照明设计分析方法。在具体的设计流程中,导入TRIZ理论的“物质-场与标准解”问题分析与求解工具,将标准解转为可被景观疏散照明设计应用的设计依据,据此完成设计方案。将方案以VR虚拟仿真场景的方式应用于景观疏散照明设计仿真实验中,请专家用户利用VR设备进入场景对方案进行主观评价以此验证模型的可行性。可知具体的景观疏散照明设计与用户视觉注意机制能够形成匹配,关注用户的注意力可以提升人流疏散效率。

关键词：照明设计人流疏散视觉注意机制 TRIZ物质-场 VR仿真

Removal of Hes during Anaerobic Bioconversion of Dairy Manure

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Chinese Journal of Chemical Engineering 2009年第2期17卷 273-277页

作者： jam.saifullah Lar 李秀金 Department of Environmental science and Engineering Beijing University of Chemical Technology Beijing 100029 China Department of Chemistry Government Degree College Uch Sharif Bahawalpur Pakistan

The main aim of this research w.s the experimental study at lab scale to check the absorption technology for the in situ removal of H2s from biogas during anaerobic digestion process. The reagent FeCl3 w.s used to check the removal efficiency of H2s produced from dairy manure during anaerobic bioconversion process. The experiments w.re conducted under mesophilic conditions. The composition of biogas w.s analyzed by gas chromatography analyzer equipped w.th flame photometer and thermal conductivity detectors. Experimental results under the same conditions demonstrate that high concentration of H2s in the form of Fes can be removed totally from the biogas using FeCl3 dosing w.th in anaerobic batch digester.

关键词： anaerobic digestion biogas dairy manure FeCl3 hydrogen sulfide

基于改进YOLOv8s的无人机目标检测算法

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国外电子测量技术 2024年第7期43卷 14-23页

作者：曲晨阳吕进卫策长安大学信息工程学院西安710000

针对目前无人机航拍图像目标尺寸较小,图像背景复杂,导致现有的无人机目标检测算法检测精度较低的问题,提出一种改进YOLOv8s的无人机目标检测算法。首先使用可变形卷积替换标准卷积,以增强网络对不规则形状目标的特征提取能力;然后使用... 详细信息

针对目前无人机航拍图像目标尺寸较小,图像背景复杂,导致现有的无人机目标检测算法检测精度较低的问题,提出一种改进YOLOv8s的无人机目标检测算法。首先使用可变形卷积替换标准卷积,以增强网络对不规则形状目标的特征提取能力;然后使用可分离大核注意力机制(LsKA)改进快速空间金字塔池化(sPPF)模块,改善因目标尺度差异较大导致检测精度较低的问题。在网络颈部结合双向特征金字塔网络(Bi-FPN)实现多尺度特征融合,改善网络对小目标的漏检和错检问题。在网络头部,使用自注意力机制动态检测头(DyHead)替换原检测头,增强对遮挡物体和小目标的检测能力。最后,针对数据集中存在大量低质量样本对训练过程产生负面影响的问题,使用w.se-IOU损失函数,提升模型收敛速度和检测精度。实验结果表明,改进后的方法在VisDrone2019数据集上获得了41.7%的平均精度均值(mAP),与原YOLOv8s算法相比,mAP@0.5提升了3.0%,mAP@0.5∶0.95提升了1.9%,参数量下降了17.5%,计算量下降了12.63%。实现了模型轻量化和检测精度双重提升。

关键词：无人机目标检测可变形卷积 YOLOv8s 注意力机制