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Damage evolution and removal behaviors of GaN crystals involved in double-grits grinding

International Journal of Extreme Manufacturing 2024年第2期6卷 469-484页

作者： Chen Li Yuxiu Hu Zongze Wei Chongjun Wu Yunfeng Peng Feihu Zhang Yanquan Geng State Key Laboratory of Robotics and System(HIT) Harbin Institute of TechnologyHarbin 150001People’s Republic of China Key Laboratory of Microsystems and Microstructures Manufacturing(HIT) Harbin Institute of TechnologyHarbin 150001People’s Republic of China College of Mechanical Engineering Donghua UniversityShanghai 201620People’s Republic of China Department of Mechanical and Electrical Engineering Xiamen UniversityXiamen 361005People’s Republic of China

Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research *** this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically *** results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one *** grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance ***,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation *** interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding *** results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,*** atoms,high-pressure phase transition,dislocations,stacking faults,and lattice *** results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.

关键词： grinding double-grits molecular dynamics damage material removal gallium nitride

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Bi-Directional and Triangular Circulation Fusion Neural Networks for Small Object Detection

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IEEE Transactions on Circuits and systems for Video technology 2024年第6期35卷 5140-5152页

作者： Li, Fangyu Duan, Junzhu Zhang, Qiyu Shan, Caifeng Han, Honggui the School of Information Science and Technology Beijing Key Laboratory of Computational Intelligence and Intelligent System Engineering Research Center of Digital Community Ministry of Education Beijing Artificial Intelligence Institute Beijing University of Technology Beijing100124 China the State Key Laboratory for Novel Software Technology Nanjing University Nanjing210023 China the School of Intelligence Science and Technology Nanjing University Suzhou215163 China

Deep learning-driven object detection models are capable of accurately identifying and localizing objects. However, small objects contain limited information relative to global features, resulting in the fact that detection models often do not learn small object features adequately. To enhance the precision in detecting small objects, we propose a bi-directional and triangular circulation fusion neural network (BTFN). First, to selectively strengthen the position features of small objects, we propose a feature circulation extraction module composed of a bi-directional triangular densely nested convolutional network (BTF), thus achieving repetitive multi-layer feature fusion. Second, to fill up the semantic gaps between different scales of features, we design a mixed dual attention module (MDA) in the bi-directional triangular densely nested network. Third, to mitigate the lost information in the neural networks with deep layers as well as improve the inference time, we design a re-parameterization bi-directional composite feature fusion module (Rep-BFM) that fuses the features of multiple scales. The proposed model is evaluated extensively on the MS COCO, Tsinghua-Tencent 100k, and Haier dismantled parts of used home appliances datasets. The experiment results show that the proposed model improves the AP on MS COCO by 4%, especially the APS of small objects is improved by 7.7% compared with SOTA models. © 2024 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.

关键词： Domestic appliances

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Nutrient dynamics and cross shelf transport in the East China Sea

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Acta Oceanologica Sinica 2024年第10期43卷 48-62页

作者： Shuhang Dong Sumei Liu Jingling Ren Feng Zhou Jing Zhang Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Marine Chemistry Theory and TechnologyMinistry of EducationOcean University of ChinaQingdao 266100China Laboratory for Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200062China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China

To understand the temporal and spatial variations in nutrient dynamics,as well as the potential cross-shelf transport of nutrients between the East China Sea(ECS)shelf and the northwestern Pacific Ocean,six field observations covering the ECS were conducted in spring,summer,and autumn in 2011 and *** dynamics in the ECS and nutrient exchange between shelf water and the open ocean were *** concentrations of dissolved inorganic nutrients were detected in the nearshore surface layer and offshore bottom layer in different seasons,and the concentrations of dissolved inorganic nutrients in surface seawater were lower in summer and autumn than in *** concentrations of dissolved organic nutrients in Kuroshio surface water were slightly lower in summer than in spring,but the concentrations in Kuroshio subsurface water were slightly higher in summer than in *** were abundant nutrient reservoirs in the euphotic zone of the ECS,which explained the high primary *** evaluation of cross-shelf transport indicated that nutrients from shelf water were transported out across the 200 m isobath through the surface layer with the density(σ)less than 23.0 kg/m^(3) in *** flux of dissolved inorganic nitrogen transported from the ECS shelf to the Northwest Pacific Ocean in spring was equivalent to 21%of the atmospheric nitrogen deposition in the Northwest Pacific *** summer,the onshore flux in the surface and bottom layers accounted for 80%of the total flux,and the transportation of nutrients along the surface layer to the continental shelf contributed to the nutrient storage and primary productivity of the euphotic zone in the ECS shelf in summer.

关键词： nutrients cross shelf transportation Kuroshio East China Sea(ECS) Northwest Pacific Ocean

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Analysis of pulsation characteristics of water discharge under long pulse 51

Analysis of pulsation characteristics of water discharge und...

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51st IEEE International Conference on Plasma Science, ICOPS 2024 and 4th Asia-Pacific Conference on Plasma and Terahertz Science, APCOPTS 2024

作者： Zhao, Z. Li, X. Lan, M. Zheng, P. Zheng, W. Song, Y. Chongqing Uinversity State Key Laboratory of Power Transmission Equipment & System Security and New Technology School of Electrical Engineering Chongqing China

ISBN: (纸本)9798350360912

Pulse discharge in water can trigger powerful shock waves, which have been widely used in fields such as electro-hydraulic forming, rock fragmentation, and oil and gas production. The pulsation during discharge has a direct effect on the intensity of shock waves. Therefore, the study of pulsation characteristics is of great practical significance. At present, the analysis of pulsation characteristics is mainly focused on conditions of short pulse. However, due to the difference in time scale, these studies are limited to a single early arc or late bubble, while the development of arc and bubble under long pulse presents a strong coupling, and the underlying mechanism is still unclear. © 2024 IEEE.

关键词： Rock bursts

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Regularized automatic frequency response function acquisition of a milling robot operating in a high-dimensional workspace

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Science China(Technological Sciences) 2024年第6期67卷 1783-1797页

作者： LUO WenLong TANG XiaoWei MA Tao GUO QiuShuang XU YanYan YUAN Xing ZHANG Lei MAO XinYong School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan430074China State Key Laboratory of Smart Manufacturing for Special Vehicles and Transmission System Baotou014030China Wuhan Heavy Duty Machine Tool Group Corporation Wuhan430205China

Because robotic milling has become an important means for machining significant large parts,obtaining the structural frequency response function(FRF)of a milling robot is an important basis for machining process ***,because of its articulated serial structure,a milling robot has an enormous number of operating postures,and its dynamics are affected by the motion *** accurately obtain the FRF in the operating state of a milling robot,this paper proposes a method based on the structural modification *** the traditional excitation method,the proposed method uses robot joint motion excitation instead of hammering excitation to realize *** address the problem of the lack of information brought by motion excitation,which leads to inaccurate FRF amplitudes,this paper derives the milling robot regularization theory based on the sensitivity of structural modification,establishes the modal regularization factor,and calibrates the FRF *** to the commonly used manual hammering experiments,the proposed method has high accuracy and reliability when the milling robot is in different *** the measurement can be performed directly and automatically in the operation state,and the problem of inaccurate amplitudes is solved,the proposed method provides a basis for optimizing the machining posture of a milling robot and improving machining efficiency.

关键词： milling robot structural dynamics frequency response function automatic identification modal regularization factor high-dimensional workspace

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Safety monitoring method for powerline corridors based on single‐stage detector and visual matching

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High Voltage 2024年第4期9卷 805-815页

作者： Jinheng Li Hanbo Zheng Peng Liu Yanshen Liang Feng Shuang Junjie Huang Guangxi Key Laboratory of Power System Optimization and Energy Technology Guangxi UniversityNanningChina China Southern Power Grid Guangxi Power Grid Company Ltd. NanningChina State Grid Hubei Electric Power Research Institute WuhanChina

Effective monitoring and early warning of overhead power lines are critical for ensuring power supply stability and personnel ***,existing methods that rely solely on single vision or light detection and ranging(LiDAR)have limitations such as numerous invalid alarms,hardware equipment constraints,and lack of real-time monitoring *** article proposes an intelligent monitoring method for safety distance of the powerline corridor based on heterogeneous sensor ***,an optimised single-stage detector is designed to detect safety hazard *** the detector,the backbone network and the sample matching strategy are improved;in addition,the learning strategy is ***,the pose transformation relationship is obtained through the visual matching of prior LiDAR information and *** back projection transformation of 2D–3D is achieved according to the ***,a monocular camera-based end-to-end distance measurement scheme is proposed by combining 2D object information with coordinate transformation *** scheme is applied to the distance measurements from hazard objects to *** experimental results show that the optimisation method improves the detection accuracy and reduces the computational complexity of the ***,case experiments with continuous frame data verify the effectiveness of the safety distance monitoring scheme.

关键词： visual hardware matching

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Robust Transmission Design for Covert Satellite Communication systems With Dual-CSI Uncertainty

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IEEE Internet of Things Journal 2025年第12期12卷 21892-21903页

作者： Jia, Huaiqi Wang, Ying Wu, Wen Yuan, Jun Beijing University of Posts and Telecommunications State Key Laboratory of Networking and Switching Technology Beijing100876 China Peng Cheng Laboratory Frontier Research Center Shenzhen518000 China Joint Laboratory of Technology and Applications on Frequency Orbital Space Information Networks China Satellite Network System Research Institute Co Ltd Beijing100070 China

In this paper, we investigate a novel covert transmission scheme for satellite communication systems. Specifically, the satellite employs a rate-splitting multiple access technique to covertly transmit messages to multiple users and simultaneously transmit jamming signals, thereby enhancing the covert rate and robustness while avoiding detection by a warden. Due to the long propagation delay and lack of the warden's precise location information, acquiring perfect channel state information (CSI) between the satellite, covert users, and the warden is difficult. To this end, we establish a dual-CSI uncertainty model, which incorporates phase and norm-bounded uncertainty for the covert and wiretap channels to characterize the actual CSI. In addition, we formulate a stochastic optimization problem with the objective of maximizing the minimum covert rate while adhering to covert communication constraints. The optimization problem is non-convex and difficult to solve directly due to the dual-CSI uncertainty and the coupled nature of the variables. To solve the problem, we reformulate the original problem into a series of convex optimization problems by utilizing semidefinite relaxation, fractional programming, and the S-procedure methods. Then, we propose a robust Common Rate Allocation and Beamforming (CRAB) algorithm to obtain near-optimal solutions for the beamforming vectors and common rate allocation. Extensive simulation results demonstrate that the proposed algorithm significantly outperforms baseline schemes in terms of both covert rate and robustness. © 2014 IEEE.

关键词： Satellite communication systems

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Energy-Consumption Optimization Control for Lunar Rover's Travel with Torque-Distribution-strategy in Rear Wheels

Energy-Consumption Optimization Control for Lunar Rover's Tr...

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IEEE International Conference on Control Science and systems Engineering (CCSSE)

作者： Delun Li Jianfei Cao Yiliang Chen Zongwu Xie State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing China

ISBN: (数字)9798331517199

ISBN: (纸本)9798331517205

In anticipation of future extensive lunar surface operations, lunar rovers are required to advance towards higher speeds and improved energy conservation. When traveling at high speeds on the lunar surface, the vehicle's energy expenditure is greatly amplified by the influence of the terrain, particularly in conditions where driving and steering are coupled. This paper proposes an energy-saving control strategy for lunar rovers that employs dynamic rear-axle torque distribution, with the goal of optimizing transient energy consumption during travel. To tackle the challenge of non-differentiable functions within the optimization objectives, we suggest using a zeroth-order gradient optimization method for resolution, dynamically constraining the range of control parameters to fulfill the dynamic torque distribution objectives as needed for the task. The energy-saving control effectiveness of the algorithm has been confirmed through simulation, demonstrating a minimum energy-saving ratio of at least 4%, which increases to over 11% as the speed level rises, offering a valuable technical solution for the energy optimization of lunar rovers.

关键词： Space vehicles Energy consumption Torque Distribution strategy Moon Wheels Optimization methods systems engineering and theory Vehicle dynamics Transient analysis

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Dynamic Behavior of Suspended Bubbles in Insulating Oil Correlation with Flow Field Distribution 4th

Dynamic Behavior of Suspended Bubbles in Insulating Oil Corr...

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4th International Symposium on Insulation and Discharge Computation for Power Equipment, IDCOMPU 2023

作者： Zhang, Ning Hao, Jian Liu, Shili Zhang, Junyi Chen, Houhe Liao, Ruijin Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132012 China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing400044 China

ISBN: (纸本)9789819974122

In recent years, arcing faults inside large oil-immersed power transformers have been frequent. Suspended bubbles, as the main product of high temperature, high humidity, material aging and cracking gas production inside transformers, are one of the main causes of arcing inside transformers. However, due to the complex structure of the oil channel and the large fluctuation of the internal flow field distribution, the resulting bubble morphology evolution and movement law is not clear. In this paper, the influence of the initial position of bubbles and the relative position between bubbles on the flow field distribution is fully considered, and the dynamic behavior of suspended bubbles in oil under two fluid forms of natural oil circulation and forced oil circulation is simulated and studied by combining laminar and turbulent flow models and bubble force control equations, and the correlation mechanism between suspended bubbles and flow field distribution characteristics is analyzed. The simulation results show that the flow field in the laminar state affects the bubble aggregation and trajectory, while the turbulent state affects the bubble distortion and motion time, and a reasonable model in the simulation of bubble dynamic behavior is more beneficial to improve the simulation accuracy. © Beijing Paike Culture Commu. Co., Ltd 2024.

关键词： Flow fields

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Graphene photodetectors integrated with silicon and perovskite quantum dots

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Microsystems & Nanoengineering 2024年第3期10卷 21-33页

作者： Kashif Abbas Peirui Ji Naveed Ullah Shareen Shafique Ze Zhang Muhammad Faizan Ameer Shenghan Qin Shuming Yang State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China Department of Microelectronic Science and Engineering Laboratory of Clean Energy Storage and ConversionSchool of Physical Science and TechnologyNingbo Collaborative Innovation Center of Nonlinear Calamity System of Ocean and AtmosphereNingbo UniversityNingbo 315211China

Photodetectors(PDs)play a crucial role in imaging,sensing,communication systems,***(Gr),a leading two-dimensional material,has demonstrated significant potential for photodetection in recent ***,its relatively weak interaction with light poses challenges for practical *** integration of silicon(Si)and perovskite quantum dots(PQDs)has opened new avenues for Gr in the realm of next-generation *** review provides a comprehensive investigation of Gr/Si Schottky junction PDs and Gr/PQD hybrid PDs as well as their *** operating principles,design,fabrication,optimization strategies,and typical applications of these devices are studied and *** these discussions,we aim to illuminate the current challenges and offer insights into future directions in this rapidly evolving field.

关键词： quantum discussions summarized

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