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A fast calculation method for three-impulse contingency return trajectory during the near-moon phase based on differential algebra

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Chinese Journal of Aeronautics 2025年第4期38卷 286-304页

作者： Lin LU Haiyang LI Tianshan DONG Wanmeng ZHOU College of Aerospace Science and Technology National University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China Beijing Institute of Spacecraft System Engineering Beijing 100094China China Astronaut Research and Training Center Beijing 100094China

Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is ***,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special ***,a calculation model of three-impulse contingency return trajectories is ***,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics ***,the performance of the proposed methods is verified by numerical *** results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy *** to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed *** findings can be used for the design of contingency return trajectories in future manned lunar landing missions.

关键词： Manned lunar landing Contingency return trajectory Trajectory calculation method Differential algebra Trajectory characteristic analysis

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Oxygen functionalization-assisted anionic exchange toward unique construction of flower-like transition metal chalcogenide embedded carbon fabric for ultra-long life flexible energy storage and conversion

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Carbon Energy 2024年第1期6卷 72-93页

作者： Roshan M.Bhattarai Kisan Chhetri Nghia Le Debendra Acharya Shirjana Saud Mai Cao Hoang Phuong Lan Nguyen Sang Jae Kim Young Sun Mok Department of Chemical Engineering Jeju National UniversityJejuRepublic of Korea Department of Nano Convergence Engineering Jeonbuk National UniversityJeonjuRepublic of Korea Regional Leading Research Center(RLRC)for Nanocarbon-based Energy Materials and Application Technology Jeonbuk National UniversityJeonjuRepublic of Korea Department of Chemistry Mississippi State UniversityStarkvilleMississippiUSA Nanomaterials and System Laboratory Department of Mechatronics EngineeringJeju National UniversityJejuRepublic of Korea

The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion *** NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside *** obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode ***,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed ***,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and ***,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.

关键词： carbon cloth energy conversion energy storage flexible metal embedding ultra-stable

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Knowledge-driven material design platform based on the whole-process simulation and modeling

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International Journal of Modeling, simulation, and Scientific Computing 2022年第2期13卷 1-15页

作者： Gongzhuang Peng Tie Li Xiang Zhai Wenzheng Liu Heming Zhang National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 P.R.China Shanghai Electro-Mechanical Engineering Institute Shanghai 201109 P.R.China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing 100854 P.R.China Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation Center Beijing 100854P.R.China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center Beijing 100854P.R.China National CIMS Engineering Research Center Tsinghua University Beijing 100084P.R.China

In order to realize the agility,collaboration and visualization of alloy material devel-opment process,a product development platform based on simulation and modeling technologies is established in this *** this platform,the whole-process simulation module builds multi-level simulation models based on metallurgical mechanisms from the production line level,the thermo-mechanical coupling field level and the microstructure evolution *** design knowledge management module represents the multi-source heterogeneous material design knowledge through ontology model,including customers’requirement knowledge,material component knowledge,process design knowledge and quality inspection knowledge,and utilizes the case-based reasoning approach to reuse the *** data-driven modeling module applies machine learning algorithms to mine the relationships between product mechanical properties,material components,and process parameters from historical samples,and utilizes multi-objective optimiza-tion algorithms to find the optimal combination of process *** of the developed platform in actual steel mills shows that the proposed method helps to improve the efficiency of product design process.

关键词： Product development knowledge-based engineering multi-scale simulation performance prediction model

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An end-to-end repair-based joint training framework for weakly supervised pavement crack segmentation

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Multimedia Tools and applications 2024年第16期84卷 1-19页

作者： Zhou, Hui Tao, Huanjie Duan, Qianyue Hu, Zhenwu Deng, Yishi School of Computer Science Northwestern Polytechnical University Xi’an710129 China School of Cyberspace Security Northwestern Polytechnical University Xi’an710129 China Engineering Research Center of Embedded System Integration Ministry of Education Xi’an710129 China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Xi’an710129 China

Weakly supervised pavement crack segmentation aims to assign each pixel of pavement surface images a category label (crack or non-crack) using limited annotation information. Most existing methods adopt the multi-stage approach based on the class activation map (CAM), which outputs from a pre-trained crack classification model, to generate the pixel-level pseudo labels, and then train a segmentation model using these pseudo labels. However, these methods have two notable drawbacks: (i) CAM focuses primarily on the most discriminative regions of the image, potentially resulting in an incomplete estimation of crack regions, and (ii) the process of obtaining pixel-level pseudo labels from CAM is complex and may introduce noise. To avoid these issues, we propose an end-to-end repair-based joint training framework for weakly supervised pavement crack segmentation. Specifically, to better guide the model to pay more attention to the repair process of crack regions, we introduce the segmentation loss, which assigns different weights for crack regions and background regions, through the Residual Project Network. Additionally, to alleviate the impact of the domain gap between synthetic and real datasets, we introduce the consistency loss through the joint training paradigm of unpaired data that incorporates both crack and non-crack images into the training process simultaneously. Furthermore, to enable the model to effectively extract local features and reduce the model's computational complexity, we introduce the Lightweight Multi-head Self-attention module. The experiment results on the CRACK500 Dataset, the CFD Dataset, and the AEL Dataset demonstrate that our model achieves better performance than some existing weakly supervised pavement segmentation methods. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.

关键词： Repair

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Single-atom Pd anchored in the porphyrin-center of ultrathin 2D-MOFs as the active center to enhance photocatalytic hydrogen-evolution and NO-removal

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Chinese Chemical Letters 2024年第9期35卷 364-368页

作者： Xingyan Liu Chaogang Jia Guangmei Jiang Chenghua Zhang Mingzuo Chen Xiaofei Zhao Xiaocheng Zhang Min Fu Siqi Li Jie Wu Yiming Jia Youzhou He Chongqing Key Laboratory of Catalysis and New Environmental Materials College of Environment and ResourcesChongqing Technology and Business UniversityChongqing 400067China School of Pharmacy North Sichuan Medical CollegeNanchong 637100China Carbon Neutrality Technology Application Research Center College of River and Ocean EngineeringChongqing Jiaotong UniversityChongqing 400074China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China National Local Joint Engineering Research Center for Road Engineering and Disaster Prevention and Reduction Technology in Mountainous Areas China Merchants Chongqing Communications Technology Research and Design Institute Co.Ltd.Chongqing 400067China Chongqing Culture Relics and Archaeology Research Institute Chongqing 400013China

Single-atom catalysts were widely used to treat atmospheric pollution and alleviate energy crises through ***,how to prevent the aggregation of single atoms during the preparation and catalytic processes remained a great ***,a novel ultrathin two-dimensional porphyrin-based single-atom photocatalyst Ti-MOF(abbreviated as TMPd)obtained through a simple hydrothermal synthesis strategy was used for photocatalytic hydrogen evolution and NO removal,in which the singleatom Pd tightly anchored in the center of porphyrin to ensure single-atom Pd stable *** with most reported MOFs-based photocatalysts,the TMPd showed an excellent hydrogen evolution rate(1.32 mmol g^(-1)h^(-1))and the NO removal efficiency(62%)under visible light *** high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM)and synchrotron-radiation-based X-ray absorption fine-structure spectroscopy(XAFS)proved that pd in TMPd existed in an isolated state,and the atomic force microscope(AFM)proved the ultrathin morphology of *** calculations had demonstrated that single-atom Pd could serve as the active center and more effectively achieve electron transfer,indicating that single-atom Pd played a vital role in photocatalytic hydrogen *** addition,a possible photocatalytic pathway of NO removal was proposed based on ESR and in-situ infrared spectra,in which the catalysts anchored with single-atom Pd could produce more active substances and more effectively oxidize NO to NO_(2)^(-)or NO_(3)^(-).The results suggested that coordinating single-atom metal species as the active site in the center of porphyrin could be a feasible strategy to obtain various ultrathin porphyrin-based single-atom photocatalysts to acquire excellent photocatalytic performance further.

关键词： Porphyrin-based MOFs Single-atom Pd Ultrathin 2D nanosheets Hydrogen evolution NO removal

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Spatiotemporal deformation analysis of glaciers and surrounding landscapes in the Shishapangma region using InSAR techniques

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Journal of Mountain Science 2025年第1期22卷 210-229页

作者： LIANG Wenli LIU Rui JI Qin KOU Pinglang Chongqing Key Laboratory of GIS Application School of Geography and TourismChongqing Normal UniversityChongqing 401331China National Earth System Science Data Center Beijing 100000China Chongqing Engineering Research Center of Spatial Big Data Intelligent Technology Chongqing University of Posts and TelecommunicationsChongqing 400065China Key Laboratory of Tourism Multisource Data Perception and Decision Ministry of Culture and Tourism(TMDPDMCT)Chongqing University of Posts and TelecommunicationsChongqing 400065China

Glacier dynamics in the Himalayan midlatitudes,particularly in regions like the Shishapangma,are not yet fully understood,especially the localized topographic and climatic impacts on glacier *** study analyzes the spatiotemporal characteristics of glacier surface deformation in the Shishapangma region using the Small Baseline Subset(SBAS)Interferometric Synthetic Aperture Radar(In SAR)*** analysis reveals an average deformation rate of-4.02±17.65 mm/yr across the entire study area,with glacier regions exhibiting significantly higher rates of uplift(16.87±13.20 mm/yr)and subsidence(20.11±14.55 mm/yr)compared to non-glacier *** identifies significant surface lowering on the mountain flanks and localized uplift in certain catchments,emphasizing the higher deformation rates in glacial areas compared to non-glacial *** found a strong positive correlation between temperature and cumulative deformation(correlation coefficient of 0.63),particularly in glacier areas(0.82).The research highlights the role of temperature as the primary driver of glacier wastage,particularly at lower elevations,with strong correlations found between temperature and cumulative *** also indicates the complex interactions between topographic features,notably,slope gradient,which shows a positive correlation with subsidence rates,especially for slopes below 35°.South-,southwest-,and west-facing slopes exhibit significant uplift,while north-,northeast-,and east-facing slopes predominantly ***,we identified transition zones between debris-covered glaciers and clean ice as areas of most intense deformation,with average rates exceeding 30 mm/yr,highlighting these as potential high-risk zones for *** study comprehensively analyzes the deformation characteristics in both glacier and non-glacier areas in the Shishapangma region,revealing the complex interplay of topographic,climatic,and hydrological factors influencing glacier dynamic

关键词： Glacier melting SBAS-InSAR Topographic factors Temperature change Middle Himalayas

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Pattern Analysis and Placement Optimization of the Four-horn Monopulse for Terahertz Communication

Pattern Analysis and Placement Optimization of the Four-horn...

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2023 Cross Strait Radio Science and Wireless technology Conference, CSRSWTC 2023

作者： Lu, Yong-Han Zhu, Zhong-Bo Ma, Jing Shi, Bin Zhang, Yu-Ting Peng, Lin Guilin University of Electronic Technology Key Laboratory of Microwave and Optical Wave Application Technology Guangxi Guilin541004 China National Key Laboratory of Science and Technology on Space Microwave Xi'an710100 China Beijing Simulation Center Science and Technology on Special System Simulation Laboratory Beijing100854 China School of Optoelectronic Engineering Guangxi Key Laboratory of Optoelectronic Information Processing Guilin University of Electronic Technology Guilin541004 China

ISBN: (纸本)9798350358971

The mobile node communication in terahertz monopulse system requires narrow beam to align with the mobile target precisely. In this paper, the radiation pattern of four-horn monopulse antenna is analyzed by use of the geometric optics (GO) and aperture field integration method (AFIM), and an efficient placement optimization to reduce the beamwidth of four-horn monopulse is presented. The optimization combines the genetic algorithm (GA) with GO-AFIM. The GA is employed to seek the optimal positions of the four horns, and the GO and AFIM are introduced into the fitness function of GA to evaluate the individual fitness. The optimization result has narrowed the beamwidth and enhanced gain of radiation pattern. Compared with the simulation in full wave software, the proposed method costs less time in pattern analysis and performs more efficiently in placement optimization. © 2023 IEEE.

关键词： aperture field integration method (AFIM) geometric optics (GO) placement optimization terahertz monopulse

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SC-GNN: A Communication-Efficient Semantic Compression for Distributed Training of GNNs 24

SC-GNN: A Communication-Efficient Semantic Compression for D...

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61st ACM/IEEE Design Automation Conference, DAC 2024

作者： Wang, Jihe Wu, Ying Wang, Danghui School of Computer Science Northwestern Polytechnical University Xi'an China Engineering Research Center of Embedded System Integration Ministry of Education Northwestern Polytechnical University Xi'an China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Northwestern Polytechnical University Xi'an China

ISBN: (纸本)9798400706011

Training big graph neural networks (GNNs) in distributed systems is quite time-consuming mainly because of the ubiquitous aggregate operations that involve a large amount of cross-partition communication for collecting embeddings/gradients during the forward and backward propagation. To reduce the volume of the communication, some recent approaches focused on decaying each of connections via sampling, quantifying, or delaying until satisfactory trade-off are obtained between volume and accuracy. However, when applied to popular GNNs, those approaches are found to be bounded by a common volume/accuracy Pareto frontier which shows that the decaying for individual connection cannot further accelerate the aggregate of training. In this work, SC-GNN, a semantic compression of the cross-partition communication, is proposed to concentrate a group of connections as a high-level semantics and transmit to a target partition. Since carrying the overall intent of a group, the semantics can keep transferring the interactions, i.e., embeddings/gradients, between a pair of remote partitions until GNN models converge. In addition, a connection-pattern based differential optimization is proposed to further prune those weak connections, while guaranteeing the training accuracy. The results show that, for multi-field datasets, the compression rate of SC-GNN is 40.8 × higher than SOTA methods and the epoch time is reduced to 31.8% on average. © 2024 Copyright is held by the owner/author(s). Publication rights licensed to ACM.

关键词： Graph neural networks

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CW-YOLO: joint learning for mask wearing detection in low-light conditions

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Frontiers of Computer Science 2023年第6期17卷 191-193页

作者： Mingqiang GUO Hongting SHENG Zhizheng ZHANG Ying HUANG Xueye CHEN Cunjin WANG Jiaming ZHANG School of Computer Science China University of GeosciencesWuhan 430074China National Engineering Research Center of Geographic Information System Wuhan 430074China Wuhan Zondy Cyber Technology Co.Ltd. Wuhan 430074China Shenzhen Data Management Center of Planning and Natural Resources Shenzhen 518000China Key Laboratory of Urban Land Resources Monitoring and Simulation(Ministry of Natural Resources) Shenzhen 518000China College of Engineering Boston UniversityBoston 02215USA

1 Introduction With the rapid progress of Artificial Intelligence(AI)technology in object detection and face recognition,deep learning methods for face mask wearing detection have become increasingly mature and continuously take into account the needs of efficiency and ***,these conventional detection methods mostly ignore the complexity of real-world application scenarios,such as extremely darkness and gloomy *** unfavorable conditions lead to a series of image degradations that seriously hamper machine vision *** camera parameter adjustment,auxiliary lighting,or pre-processing enhancement[1]can weaken these negative effects to some extent to promote the detection,they will also result in increased hardware and time costs.

关键词： hardware lighting weather

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Enhanced-performance self-powered photodetector based on multi-layer MoS_(2) sandwiched between two asymmetric graphene contacts

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Science China(Technological Sciences) 2022年第11期65卷 2658-2666页

作者： GUO JunXiong LI ShangDong LIN Lin CAI Ji CHEN JianBo WANG ShiCai GOU Xin YE JingHua LUO ZhengHua HUANG Wen School of Electronic Information and Electrical Engineering Chengdu UniversityChengdu 610106China School of Electronics and Information Technology(School of Microelectronics) Sun Yat-sen UniversityGuangzhou 510006China School of Electronic Science and Engineering(National Exemplary School of Microelectronics).University of Electronic Science and Technologyof China Chengdu 610054China College of Materials Science and Engineering Sichuan UniversityChengdu 610064China Sichuan Time Frequency Synchronization System and Application Engineering Technology Research Center Chengdu 610062China

Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging,sensing,communication,and *** most popular approach for constructing a self-powered photodetector is typically based on the fabrication of an asymmetric metal-semiconductor(MS)contact;however,this technique is seriously limited by the Fermi-level pinning ***,we report a room-temperature photodetector based on multi-layer MoS_(2) sandwiched between two separated asymmetric graphene *** photodetector was driven by the built-in electric field generated by a van der Waals(vd W)contact instead of the traditional MS *** under zero-bias voltage,the highest photoresponsivity of 0.63 AW^(-1) and a specific detectivity of 7.71×10^(12) Jones were achieved at a wavelength of 450 nm with 0.08μW cm^(-2) incident power *** with devices using symmetric contacts,a high ON/OFF current ratio of approximately 1520 and a fast response time on the order of microseconds were also observed in our asymmetric graphene contact *** experimental results may open a novel way toward the realization of vd W contacts for the fabrication of selfpowered photodetectors.

关键词： MoS_(2) graphene self-powered photodetector asymmetric contact

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