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Microstructure features induced by fatigue crack initiation up to very-high-cycle regime for an additively manufactured aluminium alloy

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Journal of Materials Science & Technology 2024年第6期173卷 247-260页

作者： Xiangnan pan Leiming Du Guian Qian Youshi Hong State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Fatigue failure can still occur beyond 107 cycles,***-high-cycle fatigue(VHCF),in many metallic materials,such as aluminium alloys and high-strength *** VHCF of high-strength steels,a fine granular area(FGA)surrounding an inclusion is commonly identified as the characteristic region of crack initiation on the fracture ***,no such FGA feature and related crack initiation behaviour were observed in VHCF of conventionally cast or wrought aluminium ***,we first reported the distinct mechanisms of crack initiation and early growth,namely the microstructure feature and the role of FGA in VHCF performance for an additively manufactured(AM)AlSi10Mg *** AM pores play a key role in fatigue crack initiation similar to that of the inclusions in high-strength steels,resulting in almost identical FGA behaviour for different materials under a range of mean stress with a stress ratio at R*** profile microstructure of FGA is identified as a nanograin layer with Si rearrangement and grain boundary *** process consumes a large amount of cyclic plastic energy making FGA undertake a vast majority of VHCF *** results will deepen the understanding of VHCF nature and shed light on crack initiation mechanism of other aluminium and AM alloys.

关键词： Aluminium alloy Additive manufacturing Nanograins Very-high-cycle fatigue(VHCF) Crack initiation Mean stress

Real-Time Intelligent Diagnosis of Co-frequency Vibration Faults in Rotating Machinery Based on Lightweight-Convolutional Neural Networks

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 264-282页

作者： Xin pan Xiancheng Zhang Zhinong Jiang Guangfu Bin Beijing Key Laboratory of Health Monitoring and Self-recovery for High-End Mechanical Equipment College of Mechanical and Electrical EngineeringBeijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Engine Health Monitoring-Control and Networking(Ministry of Education) College of Mechanical and Electrical EngineeringBeijing University of Chemical TechnologyBeijing 100029China College of Mechanical Engineering Hunan University of Science and TechnologyXiangtan 411201China

The co-frequency vibration fault is one of the common faults in the operation of rotating equipment,and realizing the real-time diagnosis of the co-frequency vibration fault is of great significance for monitoring the health state and carrying out vibration suppression of the *** engineering scenarios,co-frequency vibration faults are highlighted by rotational frequency and are difficult to identify,and existing intelligent methods require more hardware conditions and are exclusively ***,Lightweight-convolutional neural networks(LW-CNN)algorithm is proposed in this paper to achieve real-time fault *** critical parameters are discussed and verified by simulated and experimental signals for the sliding window data augmentation *** on LW-CNN and data augmentation,the real-time intelligent diagnosis of co-frequency is ***,a real-time detection method of fault diagnosis algorithm is proposed for data acquisition to fault *** is verified by experiments that the LW-CNN and sliding window methods are used with high accuracy and real-time performance.

关键词： Co-frequency vibration Real-time diagnosis LW-CNN Data augmentation

Research progress on insomnia treated by traditional Chinese medicine and acupuncture based on microbial-gut-brain axis theory

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World Journal of Clinical Cases 2024年第18期12卷 3314-3320页

作者： Li-Min pan Zhi-Bo Hong rui-Qian Guan Department of Outpatient Deputy Chief Physician The First Affiliated Hospital of Heilongjiang University of Chinese MedicineHaerbin 150010Heilongjiang ProvinceChina School of Heilongjiang University of Chinese Medicine Graduate Heilongjiang University of Chinese MedicineHaerbin 150000Heilongjiang ProvinceChina Heilongjiang University of Chinese Medicine The Second Affiliated Hospital of Heilongjiang University of Chinese MedicineHaerbin 150010Heilongjiang ProvinceChina

Insomnia,as one of the emotional diseases,has been increasing in recent years,which has a great impact on people's life and ***,researchers are eager to find a more perfect *** microbiome-gut-brain axis is a new theory that has gradually become popular abroad in recent years and has a profound impact in the field of *** recent years,traditional Chinese medicine(TCM)has played an increasingly important role in the treatment of insomnia,especially acupuncture and Chinese herbal *** is the main method of TCM in the treatment of *** paper mainly reviews the combination degree of"microorganism-gut-brain axis"theory with TCM and acupuncture under the system of *** explore the mechanism of TCM and acupuncture in the treatment of insomnia under the guidance of"microorganismgut-brain axis"theory,in order to provide a new idea for the diagnosis and treatment of insomnia.

关键词： Insomnia Microorganism Intestine-brain axis Traditional Chinese medicine Acupuncture and moxibustion

The Al_(2)O_(3)and Mn/Al_(2)O_(3)sorbents highly utilized in destructive sorption of NF_(3)

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Chinese Journal of Chemical Engineering 2024年第1期65卷 54-62页

作者： Yanfei pan Hejian Li Li Zheng Xiufeng Xu School of Chemistry and Chemical Engineering Yantai UniversityYantai 264005China

NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse ***,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse *** the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective ***,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great *** this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)*** influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown that the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to ***,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via changing hydrothermal temperatures and Mn *** results show that the Mn/Al_(2)O_(3)sorbents are more utilized than bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so *** findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).

关键词： Greenhouse gas NF_(3)destructive sorption Sorbents Al_(2)O_(3) Mn/Al_(2)O_(3) Reactivity

Flow Field Simulation and Parameter Analysis of Hydraulic Unbalanced Bionic Self-recovery Actuator for Rotary Equipment

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Journal of Bionic Engineering 2024年第1期21卷 325-343页

作者： Wei Li Xin pan Dehong Ge Jinji Gao Key Laboratory of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of High-End Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China

The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppression technology is urgently needed.A new hydraulic unbalanced bionic self-recovery system is introduced,imitating the way of manually repairing faulty *** accomplish the effect of actuator mass redistribution,the technology employs pressurized air to drive the quantitative transfer of liquid in the reservoir cavity at opposite *** can complete the online adjustment of the equipment's balancing state and suppress the unbalanced vibration of equipment in real time,which gives the equipment the ability to maintain an autonomous health state and improve equipment *** composition and working principle of the system are introduced in detail,and the key performance parameters,such as the minimum running speed and the balancing liquid transfer speed,are analyzed *** fluid-solid coupling model of the actuator was established,and the two-phase flow from inside the hydraulic unbalanced bionic self-recovery actuator was simulated under multiple working conditions and the performance parameters were quantitatively analyzed.A balancing simulation test bed was built,and its effectiveness was verified by performance parameter tests and unbalanced bionic self-recovery *** experimental results show that the mass distribution adjustment of the balancing disk can be achieved using different viscosity balancing liquid,and the response of liquid viscosity 10 cSt is faster than that of liquid viscosity 100 cSt in the process of balancing liquid transfer,and the time is reduced by more than 75%;the system can reduce the simulated rotor amplitude from 18.3μm to 10.6μm online in real time,which provides technical support for the subsequent development of a new generation of bionic intelligent equipment.

关键词： Engineering self-recovery-Bionics Simulation analysis Self-recovery regulation

A reduced-order model for fast predicting ionized flows of hypersonic vehicles along flight trajectory

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Chinese Journal of Aeronautics 2024年第1期37卷 89-105页

作者： Jingchao ZHANG Chunsheng NIE Jinsheng CAI Shucheng pan School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Science and Technology on Space Physics Laboratory China Academy of Launch Vehicle TechnologyBeijing 100076China Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China

An improved Reduced-Order Model(ROM)is proposed based on a flow-solution preprocessing operation and a fast sampling strategy to efficiently and accurately predict ionized hypersonic *** ROM is generated in low-dimensional space by performing the Proper Orthogonal Decomposition(POD)on snapshots and is coupled with the Radial Basis Function(RBF)to achieve fast prediction ***,due to the disparate scales in the ionized flow field,the conventional ROM usually generates spurious negative ***,this issue is addressed by performing flow-solution preprocessing in logarithmic space to improve the conventional ***,extra orthogonal polynomials are introduced in the RBF interpolation to achieve additional improvement of the prediction *** addition,to construct high-efficiency snapshots,a trajectory-constrained adaptive sampling strategy based on convex hull optimization is *** evaluate the performance of the proposed fast prediction method,two hypersonic vehicles with classic configurations,i.e.a wave-rider and a reentry capsule,are used to validate the proposed *** two cases show that the proposed fast prediction method has high accuracy near the vehicle surface and the free-stream region where the flow field is *** with the conventional ROM prediction,the prediction results are significantly improved by the proposed method around the discontinuities,*** shock wave and the ionized *** a result,the proposed fast prediction method reduces the error of the conventional ROM by at least 45%,with a speedup of approximately 2.0×105compared to the Computational Fluid Dynamic(CFD)*** test cases demonstrate that the method developed here is efficient and accurate for predicting ionized hypersonic flows.

关键词： Reduced-order model Radial basis function Constrained sampling Transfer function Fast flow prediction Ionized hypersonic flows

Microstructure and Mechanical Property of the Large Cross-Sectioned Mg-Gd-Y-Zn-Zr Alloy Produced by Small Extrusion Ratio

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Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 999-1006页

作者： Sen Wang Hucheng pan Caixia Jiang Zhihao Zeng Zhen pan Weineng Tang Chubin Yang Yuping Ren Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) College of Materials Science and EngineeringNortheastern UniversityShenyang110819China Mg and Mg Alloy Institute Technology CenterBaosteel Metal Co.LtdChina Baowu Steel GroupShanghai200940China Jiangxi Provincial Engineering Research Center for Magnesium Alloy Gannan Normal UniversityGanzhou341000China

In this work,the microstructure and mechanical properties of large cross-sectioned Mg-9Gd-3Y-1.2Zn-0.5Zr(VWZ931)samples produced by the small extrusion ratio has been *** as-extruded VWZ931 sample with diameter of~30 mm can exhibit the high yield strength(YS)of 339 MPa,ultimate tensile strength(UTS)of 387 MPa and elongation of 8.2%,*** peak-aged,the YS and UTS of the Mg samples were significantly increased to 435 MPa and 467 *** small extrusion ratio leads to the low fraction of dynamic recrystallized(DRX)grains in VWZ931 sample,and the texture hardening effect can be fully utilized to achieve high *** combined effect of precipitation strengthening due to the long-period stacking ordered phases and theβ′phase,grain boundary strengthening due to the fine DRX grains,heterogeneous deformation-induced strengthening caused by bimodal microstructure,can together contribute to the high strength of present Mg *** findings can shed light on designing other large-sized Mg wrought alloys with high mechanical performance.

关键词： Mg-RE alloy Mechanical property Bimodal grains Texture hardening

Mobile Crowdsourcing Task Allocation Based on Dynamic Self-Attention GANs

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Computers, Materials & Continua 2024年第4期79卷 607-622页

作者： Kai Wei Song Yu Qingxian pan School of Computer and Control Engineering Yantai UniversityYantai264005China School of Computer and Information Science Southwest UniversityChongqing400715China

Crowdsourcing technology is widely recognized for its effectiveness in task scheduling and resource *** traditional methods for task allocation can help reduce costs and improve efficiency,they may encounter challenges when dealing with abnormal data flow nodes,leading to decreased allocation accuracy and *** address these issues,this study proposes a novel two-part invalid detection task allocation *** the first step,an anomaly detection model is developed using a dynamic self-attentive GAN to identify anomalous *** to the baseline method,the model achieves an approximately 4%increase in the F1 value on the public *** the second step of the framework,task allocation modeling is performed using a twopart graph matching *** phase introduces a P-queue KM algorithm that implements a more efficient optimization *** allocation efficiency is improved by approximately 23.83%compared to the baseline *** results confirm the effectiveness of the proposed framework in detecting abnormal data nodes,enhancing allocation precision,and achieving efficient allocation.

关键词： Mobile crowdsourcing task allocation anomaly detection GAN attention mechanisms

On Leray's problem in an infinitely long pipe with the Navier-slip boundary condition

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Science China Mathematics 2024年第4期67卷 819-854页

作者： Zijin Li Xinghong pan Jiaqi Yang School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing 210044China School of Mathematics and Key Laboratory of Ministry of Industry and Information Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Mathematics and Statistics Northwestern Polytechnical UniversityXi'an 710129China

The original Leray’s problem concerns the well-posedness of weak solutions to the steady incompressible Navier-Stokes equations in a distorted pipe,which approach the Poiseuille flow subject to the no-slip boundary condition at spatial *** this paper,the same problem with the Navier-slip boundary condition instead of the no-slip boundary condition,is *** to the complexity of the boundary condition,some new ideas,presented as follows,are introduced to handle the extra difficulties caused by boundary ***,the Poiseuille flow in the semi-infinite straight pipe with the Navier-slip boundary condition will be introduced,which will serve as the asymptotic profile of the solution to the generalized Leray’s problem at spatial ***,a solenoidal vector function defined in the whole pipe,satisfying the Navierslip boundary condition,having the designated flux and equalling the Poiseuille flow at a large distance,will be carefully *** plays an important role in reformulating our ***,the energy estimates depend on a combined L2-estimate of the gradient and the stress tensor of the velocity.

关键词： stationary Navier-Stokes system Navier-slip boundary condition Leray's problem