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Experimental Study on Geometry Characteristics of Turbulent Premixed Flames for Natural Gas/Air Mixtures

Journal of Thermal Science 2025年第1期34卷 268-282页

作者： ZHENG Weilin WANG Qijiao XIAO Huahua CHEN Xiaoxiao XIE Fan ZENG Wen Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace UniversityShenyang 110136China State Key Laboratory of Fire Science University of science and Technology of ChinaHefei 230027China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

In this study,focusing on the geometry characteristics of spherical expanding flame,the turbulent premixed flames of natural gas/air mixtures were investigated in a fan-stirred turbulent *** effects of initial temperature(T=300-400 K),initial pressure(P=0.1-0.3 MPa),turbulence intensity(u'=1.0-2.7 m/s),oxygen volumetric percentage(φ(O_(2))=15%-21%)and carbon dioxide volumetric percentage(φ(CO_(2))=0-20%)were delved *** flame profile under the Cartesian coordinate system was derived from the schlieren images taken by the high-speed ***,from both macroscopic and microscopic perspectives,the influence of experimental conditions on the flame geometry characteristics was explored through flame front extraction,wavelet decomposition and network *** results demonstrate that for significant flame wrinkling,changes in species concentrations and turbulence intensity have more pronounced effects on the flame wrinkling *** wrinkling of the flame front maintains a certain degree of similarity,as evidenced by the locally concentrated distribution of the angles of the maximum fluctuation *** disturbance energy under large-scale(D6-D8)disturbances exhibits relatively high values with a similar trend,exerting a significant impact on the geometry characteristics of the flame *** peaks of correlation degree are scattered either with the decomposition scale or the development of flame radius,indicating no linear correlation between different detail ***,the probability distribution of node degrees in key wrinkled regions exhibits different trends with that of large-scale wrinkling and disturbance energy,especially with changes in initial *** occurs because the number of key wrinkles varies based on the perturbation's strength or the region's ***,an increase in the fluctuation frequency of the flame's local radius may not necessarily lead to an increase in the number of key folded regions.

关键词： geometry characteristics large-scale wrinkling wavelet decomposition network topology fan-stirred turbulent combustor

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Propagation criterion of hydraulic fracture in rock based on the rock micro-cracking mechanism

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International Journal of Mining Science and technology 2025年第3期35卷 433-449页

作者： Qingwang Cai Bingxiang Huang Xinglong Zhao Yuekun Xing School of Resources Environment and Safety Engineering University of South ChinaHengyang 421001 China State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116 China

Hydraulic fracture(HF)formed in rock significantly helps with the development of geo-energy and *** HF formation condition was challenging to understand,with obscure rock micro-cracking mechanisms being a key *** rock micro-cracking mechanism under gradient pore water pressure was analyzed on the scale of mineral particles and it was combined with macroscopic boundary conditions of rock hydraulic fracturing,obtaining the propagation criterion of HF in rock based on the rock micro-cracking mechanism which was verified by *** results show that the disturbed skeleton stress induced by the disturbance of gradient pore water pressure in rock equals the pore water pressure *** overall range of the defined mechanical shape factor a/b is around 1,but greater *** the combined influence of pore water pressure differences and macroscopic boundary stresses on the rock micro-cracking,micro-cracks form among rock mineral particles,micro-cracks connect to form micro-hydraulic fracture surfaces,and micro-hydraulic fracture surfaces open to form macrohydraulic *** begins to form at the micro-cracking initiation pressure(MCIP),which was tested by keeping the HF tip near the initiation *** theoretical value of MCIP calculated by the proposed propagation criterion is close to MCIP tested.

关键词： Hydraulic fracture Propagation criterion Micro-cracking mechanism Pore pressure Stress singularity

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Fuzzy-based risk assessment and collision avoidance strategy for unmanned surface vessels near offshore wind farm 6th

Fuzzy-based risk assessment and collision avoidance strategy...

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6th International Conference on Renewable Energies Offshore, RENEW 2024

作者： Hashali, S.D. Yang, S.L. Wu, H. Xiang, X.B. Huazhong University of Science and Technology Wuhan China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Wuhan China

ISBN: (纸本)9781032905570

The safety and efficiency of Unmanned Surface Vessels (USVs) are paramount in the increasingly complex maritime environments surrounding offshore wind farms. This paper proposes a novel fuzzy logic-based risk assessment and collision avoidance model specifically designed for USVs operating near offshore wind farms. The model utilizes the fuzzy analytic hierarchy process to accurately weigh and evaluate key factors, including the Distance to Closest Point of Approach (DCPA), Time to Closest Point of Approach (TCPA), relative distance, relative heading, and relative speed. By integrating these factors, the model provides a more precise assessment of collision risks and enhances the decision-making process for collision avoidance. The framework is aligned with the International Regulations for Preventing Collisions at Sea (COLREGS) and is validated through MATLAB simulations. The results demonstrate the model’s effectiveness in preventing collisions with multiple dynamic obstacles, significantly improving the navigation safety of USVs in challenging and confined maritime environments. © 2025 The Author(s).

关键词： Offshore wind farms

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Stabilization of zinc anode by trace organic corrosion inhibitors for long lifespan

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Chinese Chemical Letters 2025年第3期36卷 538-543页

作者： Wenfeng Shao Chuanlin Li Chenggang Wang Guangsen Du Shunshun Zhao Guangmeng Qu Yupeng Xing Tianshuo Guo Hongfei Li Xijin Xu School of Physics and Technology University of JinanJi’nan 250022China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China School of Chemistry and Chemical Engineering Shandong UniversityJi’nan 250100China School of System Design and Intelligent Manufacturing Southern University of Science and TechnologyShenzhen 518000China

Aqueous zinc-ion batteries are highly favored for their enhanced safety and reduced ***,there exist challenges including zinc dendrite,hydrogen evolution,and surface corrosion to be *** electrolyte additives is a highly convenient approach to solving zinc anode-related *** by industrial corrosion protection,a trace amount of the corrosion inhibitor urotropine(URT)is used as an electrolyte additive to protect the zinc *** calculation and experimental analysis confirm the adsorption of URT molecules onto the surface of Zn,which inhibits hydrogen *** adsorption further leads to the formation of an inorganic-organic bilayer solid electrolyte interface(SEI)on the surface of the zinc anode,effectively protecting the Zn anode from corrosion,hydrogen evolution and zinc *** presence of SEI enables symmetrical Zn//Zn cells to exhibit a long cycling performance of 1750 h at 1mA/cm^(2)and an average coulombic efficiency of 99.0%at 1mA/cm^(2)in Zn//Cu *** being coupled with polyaniline(PANI),the Zn//PANI full battery displays excellent cycle stability and specific capacity.

关键词： Solid electrolyte interface Aqueous zinc-ion battery Corrosion inhibitors Electrolyte additive Zinc anode

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LACO: A Latency-Constraint Offline Neural Network Scheduler towards Reliable Self-Driving Perception 24

LACO: A Latency-Constraint Offline Neural Network Scheduler ...

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43rd International Conference on Computer-Aided Design, ICCAD 2024

作者： Tan, Zhanhong Zhu, Zijian Wu, Mengdi Ma, Kaisheng State Key Laboratory of Intelligent Vehicle Safety Technology Chongqing China Tsinghua University Beijing China

ISBN: (纸本)9798400710773

Perception is a crucial and compute-intensive self-driving stage where multiple DNN models periodically process image and point-cloud inputs with constant intervals as latency constraints. This scenario is similar to the multistream scenario in the MLPerf benchmark but with more than one query sequence of diverse intervals from different sensors, and each query also evokes more than one model. In this paper, we call this scenario multi-multistream (M2stream). Because the periodic inputs arrive continuously, the neural network processor should process them in time to avoid information dropping and maintain self-driving safety. To this end, this paper aims to explore throughput optimization under constant deadlines for the M2-stream scenario in self-driving perception. We propose LACO, a novel LAtency-COnstraint scheduler, to optimize the task throughput under the predetermined deadline constraints. Considering that the task arrivals are known with constant intervals, we can employ an offline scheduling method. Specifically, we turn the scheduling space exploration into the Satisfiability problem (SAT) and tackle it using an off-the-shelf SAT solver. Our experiments demonstrate that LACO achieves 1.2×~2.4× throughput improvement against the baselines on an 8×8-core accelerator. LACO also shows consistent superiority in various hardware scales and input resolutions. © 2024 Copyright is held by the owner/author(s).

关键词： Deep neural networks

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Student academic performance prediction via hypergraph and TabNet

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Journal of Big Data 2025年第1期12卷 1-24页

作者： Yang, Yisheng Zhao, Shiyu An, Sufang Li, Xiaoyong Zhang, Yong Beijing Key Laboratory of Multimedia and Intelligent Software Technology Beijing University of Technology Beijing China Academic Affairs Office Beijing Open University Beijing China State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of Automation Chinese Academy of Sciences Beijing China

Student academic performance prediction plays a very important role in student management. With the development of deep learning, there has been some related research work on predicting student academic performance. Although many factors influence students’ academic performance, students at the same university tend to have similar intellectual levels and learning environments. Therefore, learning behaviors can significantly impact their academic performance. Thus, modeling students’ behavior can enable the prediction of their academic performance. However, existing methods mostly focus on modeling individual student behaviors, neglecting the complex associations among students hidden within campus behavioral data. In reality, the associations between students often involve higher-order, multi-to-multi relationships, rather than simple, pairwise connections. At the same time, most data-driven deep learning models are not interpretable. But in fact, the analysis of behaviors that affect student academic performance is more useful in many cases. To address these issues, this paper proposes a student academic performance prediction model that combines hypergraphs and TabNet. This method first processes and extracts usable behavior features from collected multi-source campus behavior data;secondly, it utilizes K-Nearest Neighbors (KNN) to construct a hypergraph to describe the higher-order associations among students;then, it uses hypergraph convolution to aggregate neighborhood features to learn sample embedding representations;finally, the academic performance of students are predicted by the TabNet model. Experimental results on real student behavior datasets indicate that the precision, recall, and F1 score of the method proposed in this paper are improved compared to baseline methods. Additionally, using hypergraphs and TabNet can help to explain the relationship between student behavior and performance at the feature level. © The Author(s) 2025.

关键词： Students

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Combining Local Electromagnetic Scattering and Global Structure Features for SAR Open Set Recognition

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IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 2025年 18卷 12572-12587页

作者： Lin, Qinjie Sun, Hao Xu, Yanjie Wang, Junyu Ji, Kefeng Kuang, Gangyao National University of Defense Technology State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology Changsha410073 China

Automatic target recognition (ATR) is crucial for synthetic aperture radar (SAR) image interpretation. However, existing SAR ATR primarily rely on algorithms from the field of computer vision, many methods have not adequately considered the imaging sensitivity of SAR images. Moreover, SAR ATR typically follows the closed set assumption, but in dynamic and open real-world environments, SAR systems may encounter target classes that have not been seen during training. To address these issues, this paper proposes a SAR open set recognition (OSR) method that combines local electromagnetic scattering and global structure features. The global structural features focus on the overall relationship between target and background, while the local electromagnetic scattering features can effectively capture the scattering characteristics of target. Hence, we construct a global and local feature guidance (GLGE) network, fuses these complementary features as prior knowledge to guide deep features. Then, a class-anchor-based loss function is constructed by Anchor loss and Tuple loss, which cluster the features of known classes targets around predefined class anchors. Finally, the distance ratio is calculated to identify known classes targets and reject unknown classes targets. The experimental results on the MSTAR and SAR-ACD datasets show that our method outperforms other OSR methods in recall, precision, F1, and accuracy, demonstrating a superior performance in OSR. © 2008-2012 IEEE.

关键词： Automatic target recognition

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High-energy-density lithium manganese iron phosphate for lithium-ion batteries:Progresses,challenges,and prospects

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Journal of Energy Chemistry 2025年第1期100卷 1-17页

作者： Bokun Zhang Xiaoyun Wang Shuai Wang Yan Li Libo Chen Handong Jiao Zhijing Yu Jiguo Tu State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Research Institute for Intelligent Wearable Systems The Hong Kong Polytechnic University Hong Kong 9977China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

The soaring demand for smart portable electronics and electric vehicles is propelling the advancements in high-energy–density lithium-ion *** manganese iron phosphate(LiMn_(x)Fe_(1-x)PO_(4))has garnered significant attention as a promising positive electrode material for lithium-ion batteries due to its advantages of low cost,high safety,long cycle life,high voltage,good high-temperature performance,and high energy *** LiMn_(x)Fe_(1-x)PO_(4)has made significant breakthroughs in the past few decades,there are still facing great challenges in poor electronic conductivity and Li-ion diffusion,manganese dissolution affecting battery cycling performance,as well as low tap *** review systematically summarizes the reaction mechanisms,various synthesis methods,and electrochemical properties of LiMn_(x)Fe_(1-x)PO_(4)to analyze reaction processes accurately and guide material ***,the main challenges currently faced are concluded,and the corresponding various modification strategies are discussed to enhance the reaction kinetics and electrochemical performance of LiMn_(x)Fe_(1-x)PO_(4),including multi-scale particle regulation,heteroatom doping,surface coating,as well as microscopic morphology ***,in view of the current research challenges faced by intrinsic reaction processes,kinetics,and energy storage applications,the promising research directions are *** importantly,it is expected to provide key insights into the development of high-performance and stable LiMn_(x)Fe_(1-x)PO_(4)materials,to achieve practical energy storage requirements.

关键词： Lithiummanganese iron phosphate High energydensity Lithium-ionbatteries Reactionmechanism Tap density

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Toward next-generation networks: A blockchain-based approach for core network architecture and roaming identity verification

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Digital Communications and Networks 2025年第2期11卷 326-336页

作者： Yi Gong Boyuan Yu Lei Yang Fanke Meng Lei Liu Xinjue Hu Zhan Xu School of Information and Communication Engineering Beijing Information Science&Technology University Xi'an University of Posts and Telecommunications Guangzhou Institute of Technology Xidian University Intelligent Transportation Systems Research Center Wuhan University of Technology State Key Laboratory of Maritime Technology and Safety

With the evolution of next-generation communication networks, ensuring robust Core Network(CN) architecture and data security has become paramount. This paper addresses critical vulnerabilities in the architecture of CN and data security by proposing a novel framework based on blockchain technology that is specifically designed for communication networks. Traditional centralized network architectures are vulnerable to Distributed Denial of Service(DDoS) attacks, particularly in roaming scenarios where there is also a risk of private data leakage, which imposes significant operational demands. To address these issues, we introduce the Blockchain-Enhanced Core Network Architecture(BECNA) and the Secure Decentralized Identity Authentication Scheme(SDIDAS). The BECNA utilizes blockchain technology to decentralize data storage, enhancing network security, stability, and reliability by mitigating Single Points of Failure(SPoF). The SDIDAS utilizes Decentralized Identity(DID) technology to secure user identity data and streamline authentication in roaming scenarios, significantly reducing the risk of data breaches during cross-network transmissions. Our framework employs Ethereum, free5GC, Wireshark, and UERANSIM tools to create a robust, tamper-evident system model. A comprehensive security analysis confirms substantial improvements in user privacy and network security. Simulation results indicate that our approach enhances communication CNs security and reliability, while also ensuring data security.

关键词： Blockchain Core network Privacy data protection Decentralized identity Roaming identity verification

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High-precision trajectory calibration for robot surface machining by meta-heuristic search algorithm from local error in machining area

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International Journal of Advanced Manufacturing technology 2025年第5期138卷 2281-2295页

作者： Bi, Guangde Lu, Lei Zhang, Lei Fan, Cheng Sun, Lining School of Mechanical and Electric Engineering Jiangsu Provincial Key Laboratory of Advanced Robotics Soochow University Suzhou215123 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

Industrial robots used in complex surface machining are gradually increasing because of their high flexibility and large workspace. However, due to their low geometric accuracy, their application in high-precision surface machining is hindered. In order to improve the machining accuracy, a high-precision robot trajectory calibration method for complex surface machining is proposed. In the machining process, the machining trajectory is usually only within a certain machining area. In the method, high-precision standard balls are set at the boundary of the machining area. Based on the precise position information of these standard balls, the trajectory of the robot in the machining area is calibrated. Compared with the global robot calibration method, the proposed method can calibrate the robot trajectory in the machining area through standard parts, which will improve the trajectory accuracy of the machining robot to the level of repeated positioning accuracy. In this method, a large amount of standard ball data is obtained by the in-place measuring device before the machining process. Then, based on these data, a meta-heuristic search algorithm is used to calibrate the kinematic deviation of the robot measurement and the machining system. The trajectory of the machining robot is adjusted by the kinematic deviation after calibration, and it is applied to the motion control of the machining process to improve the positioning accuracy of the machining trajectory. In the end, to verify the accuracy and practicability of the machining trajectory obtained by this method, measurement and machining experiments are carried out. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2025.

关键词： Industrial robots

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