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Microstructure evolution and mechanical properties of brazing joint for ultra-thin-walled Inconel 718 considering grain size effect and brazing temperature

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Chinese Journal of Aeronautics 2024年第2期37卷 541-556页

作者： Rui ZHAO Yueshuai SONG Hui KANG Min wan School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its *** achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution *** evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension *** findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing *** effects of grain size,such as pinning and splitting,are amplified at higher brazing ***,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture *** fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack ***,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.

关键词： EYWORDS Ultra-thin-walled structure Brazing Inconel 718 Grain size effect Brazing temperature

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Dynamics modeling and optimal control for multi-information diffusion in Social Internet of Things

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Digital Communications and Networks 2024年第3期10卷 655-665页

作者： Yaguang Lin Xiaoming wang Liang wang Pengfei wan School of Computer Science Shaanxi Normal UniversityXi'an710119China

As an ingenious convergence between the Internet of Things and social networks,the Social Internet of Things(SIoT)can provide effective and intelligent information services and has become one of the main platforms for people to spread and share ***,SIoT is characterized by high openness and autonomy,multiple kinds of information can spread rapidly,freely and cooperatively in SIoT,which makes it challenging to accurately reveal the characteristics of the information diffusion process and effectively control its *** this end,with the aim of exploring multi-information cooperative diffusion processes in SIoT,we first develop a dynamics model for multi-information cooperative diffusion based on the system dynamics theory in this ***,the characteristics and laws of the dynamical evolution process of multi-information cooperative diffusion are theoretically investigated,and the diffusion trend is *** this basis,to further control the multi-information cooperative diffusion process efficiently,we propose two control strategies for information diffusion with control objectives,develop an optimal control system for the multi-information cooperative diffusion process,and propose the corresponding optimal control *** optimal solution distribution of the control strategy satisfying the control system constraints and the control budget constraints is solved using the optimal control ***,extensive simulation experiments based on real dataset from Twitter validate the correctness and effectiveness of the proposed model,strategy and method.

关键词： Social Internet of Things Information diffusion Dynamics modeling Trend prediction Optimal control

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A comprehensive review of radiation effects on solder alloys and solder joints

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Defence Technology（防务技术） 2024年第9期39卷 86-102页

作者： Norliza Ismail wan Yusmawati wan Yusoff Nor Azlian Abdul Manaf Azuraida Amat Nurazlin Ahmad Emee Marina Salleh Department of Physics Centre for Defence Foundation StudiesUniversiti Pertahanan Nasional MalaysiaKem Sungai BesiKuala Lumpur 57000Malaysia Department of Mineral and Geoscience Malaysia Mineral Research CentreJalan Sultan Azlan ShahIpoh 31400PerakMalaysia

In the realm of military and defence applications, exposure to radiation significantly challenges the performance and reliability of solder alloys and joints in electronic systems. This comprehensive review examines radiation-induced effects on solder alloys and solder joints in terms of microstructure and mechanical properties. In this paper, we evaluate the existing literature, including experimental studies and fundamental theory, to provide a comprehensive overview of the behavior of solder materials under radiation. A review of the literature highlights key mechanisms that contribute to radiation-induced changes in the microstructure, such as the formation of intermetallic compounds, grain growth,micro-voids and micro-cracks. Radiation is explored as a factor influencing solder alloy hardness,strength, fatigue and ductility. Moreover, the review addresses the challenges and limitations inherent in studying the effects of radiation on solder materials and offers recommendations for future research. It is crucial to understand radiation-induced effects on solder performance to design robust and radiationresistant electronic systems. A review of radiation effects on solder materials and their applications in electronics serves as a valuable resource for researchers, engineers, and practitioners in that field.

关键词： Defence technology Solder alloy Solder joints Radiation-induced effect Microstructure Mechanical properties

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Coarse-fine joint target parameter estimation method based on AN-RSC in OFDM passive radar

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Journal of Systems Engineering and Electronics 2024年第2期35卷 339-349页

作者： wanG Chujun wan Xianrong YI Jianxin CHENG Feng School of Electronic Information Wuhan UniversityWuhan 430072China

In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to achieve better estimation accuracy of target parameters without excessive computational ***,the modulation symbol domain(MSD)method is used to roughly estimate the delay and Doppler of ***,to obtain high-precision Doppler estimation,the atomic norm(AN)based on the multiple measurement vectors(MMV)model(MMV-AN)is used to manifest the signal sparsity in the continuous Doppler *** the same time,a reference signal compensation(RSC)method is presented to obtain highprecision delay *** results based on the OFDM signal show that the coarse-fine joint estimation method based on AN-RSC can obtain a more accurate estimation of target parameters compared with other *** addition,the proposed method also possesses computational advantages compared with the joint parameter estimation.

关键词： passive radar orthogonal frequency division multiplexing(OFDM)signal atomic norm(AN) parameter estimation

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The breaking of spin symmetry in the single-particle resonances in deformed nuclei

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Nuclear Science and Techniques 2024年第3期35卷 237-245页

作者： Zhen-Yu Zheng Shou-wan Chen Quan Liu School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

The exploration of spin symmetry (SS) in nuclear physics has been instrumental in identifying atomic nucleus *** this study,we solve the Dirac equation from the relativistic mean field (RMF) in complex momentum *** investigated SS and its breaking in single-particle resonant states within deformed nuclei,with a focus on the illustrative *** was the initial discovery of a resonant spin doublet in a deformed nucleus,with the expectation of the SS approaching the continuum *** increasing single-particle energy,the splitting of the resonant spin doublets widened *** escalating splitting implies diminishing adherence to the SS,indicating a departure from the expected behavior as the energy levels *** also analyzed the width of the resonant states,showing that lower orbital angular momentum resonances possess shorter decay times and that SS is preserved within broad resonant doublets,as opposed to narrow resonant *** the radial density of the upper components for the bound-state and resonant-state doublets,it becomes evident that while SS is well-preserved in the bound states,it deteriorates in the resonant *** impact of nuclear deformation (β_(2.) on SS was examined,demonstrating that an increase in β_(2. resulted in higher energy and width splitting in the resonant spin doublets,which is attributed to increased component ***,the sensitivity of spin doublets to various potential parameters such as surface diffuseness (a),radius (R),and depth (Σ0) is discussed,emphasizing the role of these parameters in *** study provides valuable insights into the behavior of spin doublets in deformed nuclei and their interplay with the nuclear structure,thereby advancing our understanding of SS in the resonance state.

关键词： Spin symmetry Resonant states Deformed nuclei Complex-momentum representation

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A Spleen Tyrosine Kinase’s Sky in Neuronal Degeneration

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Neuroscience Bulletin 2024年第2期40卷 273-276页

作者： wan-Yun Zhang Sen Lin Department of Neurology Xinqiao HospitalThe Second Afliated HospitalArmy Medical UniversityChongqing 400042China Chongqing Institute for Brain and Intelligence Guangyang Bay LaboratoryChongqing 400064China

With the growing elderly population,neurodegenerative disorders like Alzheimer's disease(AD)are emerging as a significant public health *** is widely acknowledged in the scientific community that the accumulation of neurotoxic aggregates,such as amyloid beta(Aβ),within the central nervous system is a major factor in the development of these ***,human genome-wide association studies have identified mutations in microglial receptors that may be linked to a number of neurodegenerative diseases[1].

关键词： Aβ Spleen Alzheimer

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Dynamic changes in butyrate levels regulate satellite cell homeostasis by preventing spontaneous activation during aging

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Science China(Life Sciences) 2024年第4期67卷 745-764页

作者： Shujie Chen Liujing Huang Bingdong Liu Huimin Duan Ze Li Yifan Liu Hu Li Xiang Fu Jingchao Lin yinlan Xu Li Liu Dan wan Yulong yin Liwei Xie Department of Endocrinology and Metabolism Zhujiang HospitalSouthern Medical UniversityGuangzhou 510280China State Key Laboratory of Applied Microbiology Southern China Guangdong Provincial Key Laboratory of Microbial Culture Collection and ApplicationGuangdong Open Laboratory of Applied MicrobiologyInstitute of MicrobiologyGuangdong Academy of SciencesGuangzhou 510070China School of Public Health Xinxiang Medical UniversityXinxiang 453003China Department of Infectious Diseases Nanfang HospitalSouthern Medical UniversityGuangzhou 510515China Metabo-Profile Biotechnology(Shanghai)Co.Ltd. Shanghai 201315China Institute of Aging Research Guangdong Provincial Key Laboratory of Medical Molecular DiagnosticsSchool of Medical TechnologyGuangdong Medical UniversityDongguan 524023China Department of Rehabilitation Medicine Nanfang HospitalSouthern Medical UniversityGuangzhou 510000China Laboratory of Animal Nutritional Physiology and Metabolic Process Key Laboratory of Agro-ecological Processes in Subtropical RegionInstitute of Subtropical AgricultureChinese Academy of SciencesChangsha 410125China Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong LaboratoryGuangzhou 510005China

The gut microbiota plays a pivotal role in systemic metabolic processes and in particular functions,such as developing and preserving the skeletal muscle ***,the interplay between gut microbiota/metabolites and the regulation of satellite cell(SC)homeostasis,particularly during aging,remains *** propose that gut microbiota and its metabolites modulate SC physiology and homeostasis throughout skeletal muscle development,regeneration,and aging *** investigation reveals that microbial dysbiosis manipulated by either antibiotic treatment or fecal microbiota transplantation from aged to adult mice,leads to the activation of SCs or a significant reduction in the total ***,employing multi-omics(e.g.,RNA-seq,16S r RNA gene sequencing,and metabolomics)and bioinformatic analysis,we demonstrate that the reduced butyrate levels,alongside the gut microbial dysbiosis,could be the primary factor contributing to the reduction in the number of SCs and subsequent impairments during skeletal muscle ***,butyrate supplementation can mitigate the antibiotics-induced SC activation irrespective of gut microbiota,potentially by inhibiting the proliferation and differentiation of SCs/*** butyrate effect is likely facilitated through the monocarboxylate transporter 1(Mct1),a lactate transporter enriched on membranes of SCs and *** a result,butyrate could serve as an alternative strategy to enhance SC homeostasis and function during skeletal muscle *** findings shed light on the potential application of microbial metabolites in maintaining SC homeostasis and preventing skeletal muscle aging.

关键词： gut microbiota aging satellite cells butyrate Slc16a1(Mct1)

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Growth of RB Population in the Conversion Phase of Chlamydia Life Cycle

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Communications on Applied Mathematics and Computation 2024年第1期6卷 90-112页

作者： Frederic Y.M.wan Department of Mathematics University of CaliforniaIrvineCA92697-3875USA

Upon infecting a host cell,the reticulate body(RB)form of the Chlamydia bacteria simply proliferates by binary fission for an extended *** data show only RB units in the infected cells 2. hours post infection(hpi),spanning nearly half way through the development *** data collected every 4 hpi,conversion to the elementary body(EB)form begins abruptly at a rapid rate sometime around 2. *** modeling proliferation and conversion as simple birth and death processes,it has been shown that the optimal strategy for maximizing the total(mean)EB population at host cell lysis time is a bang-bang control qualitatively replicating the observed conversion ***,the simple birth and death model for the RB proliferation and conversion to EB deviates in a significant way from the available data on the evolution of the RB population after the onset of RB-to-EB *** working with a more refined model that takes into account a small size threshold eligibility requirement for conversion noted in the available data,we succeed in removing the deficiency of the previous models on the evolution of the RB population without affecting the optimal bang-bang conversion strategy.

关键词： Chlamydia Life cycle Optimal control Maximal infectious spread Specie competitive survival

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Synthesis of Diverse Oxetane Amino Acids via Visible-Light-Induced Photocatalytic Decarboxylative Giese-Type Reaction

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Chinese Journal of Chemistry 2024年第12期42卷 1341-1346页

作者： Haoliang Shi Yi wan Yongqiang Zhang Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism Shanghai Key Laboratory of New Drug Designand School of PharmacyEast China University of Science and TechnologyShanghai200237 China

The divergent synthesis of versatile 3,3′-disubstituted oxetane amino acids by utilizing visible-light-induced photocatalytic decarboxylative Giese-type reaction has been demonstrated.3-Methyleneoxetane-derived substrates are readily available in a single-step and highly reactive as radical acceptors,allowing the production of versatile oxetaneγ-andα-amino acids in high yields.A distinct ring strain release-driven radical addition mechanism was preliminarily *** preparative power was further highlighted by the application in the synthesis of oxetane-containing dipeptides and azetidine amino acids,as well as the transformation of the product into novel oxetane-containing spiro-heterocycle pharmacophore.

关键词： Photoredox catalysis Decarboxylative Giese-type reaction Oxetane amino acids Amino acids Synthesis Radical reactions

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Predicting Traffic Flow Using Dynamic Spatial-Temporal Graph Convolution Networks

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Computers, Materials & Continua 2024年第3期78卷 4343-4361页

作者： Yunchang Liu Fei wan Chengwu Liang School of Computer and Data Science Henan University of Urban ConstructionPingdingshan467036China School of Electrical and Control Engineering Henan University of Urban ConstructionPingdingshan467036China

Traffic flow prediction plays a key role in the construction of intelligent transportation ***,due to its complex spatio-temporal dependence and its uncertainty,the research becomes very *** of the existing studies are based on graph neural networks that model traffic flow graphs and try to use fixed graph structure to deal with the relationship between ***,due to the time-varying spatial correlation of the traffic network,there is no fixed node relationship,and these methods cannot effectively integrate the temporal and spatial *** paper proposes a novel temporal-spatial dynamic graph convolutional network(TSADGCN).The dynamic time warping algorithm(DTW)is introduced to calculate the similarity of traffic flow sequence among network nodes in the time dimension,and the spatiotemporal graph of traffic flow is constructed to capture the spatiotemporal characteristics and dependencies of traffic *** combining graph attention network and time attention network,a spatiotemporal convolution block is constructed to capture spatiotemporal characteristics of traffic *** on open data sets PEMSD4 and PEMSD8 show that TSADGCN has higher prediction accuracy than well-known traffic flow prediction algorithms.

关键词： Intelligent transportation graph convolutional network traffic flow DTW algorithm attention mechanism

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