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Multi-layer multi-pass friction rolling additive manufacturing of Al alloy:Toward complex large-scale high-performance components

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 425-438页

作者： Haibin Liu Run Hou Chenghao Wu Ruishan Xie Shujun Chen College of Mechanical&Energy Engineering Beijing University of TechnologyBeijing 100124China Chongqing Research Institute of beijing University of Technology Chongqing 401121China

At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass *** this study,multi-layer multi-pass FRAM-deposited alumin-um alloy samples were successfully prepared using a non-shoulder tool *** material flow behavior and microstructure of the over-lapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum *** results showed that a mechanical interlocking structure was formed between the adjacent layers and the adja-cent passes in the overlapped center *** friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone,which made the recrystallization degree in the left and right edge zones of the over-lapped zone the highest,followed by the overlapped center zone and the non-overlapped *** tensile strength of the overlapped zone exceeded 90%of that of the single-pass deposition *** is proved that although there are uneven grooves on the surface of the over-lapping area during multi-layer and multi-pass deposition,they can be filled by the flow of materials during the deposition of the next lay-er,thus ensuring the dense microstructure and excellent mechanical properties of the overlapping *** multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.

关键词： aluminum alloy additive manufacturing solid-state friction stir welding multi-layer multi-pass

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Effect of Nb-V microalloying on the hot deformation behavior of medium Mn steels

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 360-368页

作者： Yumeng Wang Qinyi Guo Bin Hu Haiwen Luo School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

The influence of Nb-V microalloying on the hot deformation behavior and microstructures of medium Mn steel(MMS)was investigated by uniaxial hot compression *** establishing the constitutive equations for simulating the measured flow curves,we successfully constructed deformation activation energy(Q)maps and processing maps for identifying the region of flow *** concluded the following consequences of Nb-V alloying for MMS.(i)The critical strain increases and the increment diminishes with the increasing deformation temperature,suggesting that NbC precipitates more efficiently retard dynamic recrystallization(DRX)in MMS compared with solute Nb.(ii)The deformation activation energy of MMS is significantly increased and even higher than that of some reported high Mn steels,suggesting that its ability to retard DRX is greater than that of the high Mn content.(iii)The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress,in which fine recrystallized and coarse unrecrystallized grains are present.

关键词： medium manganese steel niobium-vanadium microalloying flow behavior dynamic recrystallization hot workability

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Rock fracture mechanism of buffer blasting with cushion layer at the borehole bottom

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 325-334页

作者： Xinguang Zhu Chenxi Ding Zhe Sui Hong Su Xu Guo School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Chemical and Blasting Engineering Anhui University of Science and TechnologyHuainan 232001China

This study primarily investigates the rock fracture mechanism of bottom cushion layer blasting and explores the effects of the bottom cushion layer on rock *** involves analyses of the evolution patterns of blasting stress,characteristics of crack distribution,and rock fracture features in the ***,blasting model experiments were carried out using the dynamic caustics principle to investigate the influence of bottom cushion layers and initiation methods on the integrity of the bottom rock *** experimental results indicate that the combined use of bottom cushion layers and inverse initiation effectively protects the integrity of the bottom rock ***,the process of stress wave propagation and dynamic crack propagation in rocks was simulated using the continuum-discontinuum element method(CDEM)and the Landau explosion source model,with varying thicknesses of bottom cushion *** numerical simulation results indicate that with increasing cushion thickness,the absorption of energy generated by the explosion becomes more pronounced,resulting in fewer cracks in the bottom rock *** illustrates the positive role of the cushion layer in protecting the integrity of the bottom rock mass.

关键词： bottom cushion layer blasting crack propagation continuum-discontinuum element method dynamic stress intensity factor

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Unraveling the significance of cobalt on transformation kinetics,crystallography and impact toughness in high-strength steels

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 380-390页

作者： Yishuang Yu Jingxiao Zhao Xuelin Wang Hui Guo Zhenjia Xie Chengjia Shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic *** results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without ***,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to *** improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant ***,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant *** findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.

关键词： high-strength steel cobalt transformation kinetics crystallography impact toughness

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T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

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Neural Regeneration Research 2025年第5期20卷 1277-1292页

作者： Yuxiao Zheng Zilin Ren Ying Liu Juntang Yan Congai Chen Yanhui He Yuyu Shi Fafeng Cheng Qingguo Wang Changxiang Li Xueqian Wang School of Traditional Chinese Medicine Beijing University of Chinese MedicineBeijingChina Library Beijing University of Chinese MedicineBeijingChina Dongzhimen Hospital Beijing University of Chinese MedicineBeijingChina

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke,which promotes neuronal death and inhibits nerve tissue *** the first immune cells to be activated after an ischemic stroke,microglia play an important immunomodulatory role in the progression of the *** an ischemic stroke,peripheral blood immune cells(mainly T cells)are recruited to the central nervous system by chemokines secreted by immune cells in the brain,where they interact with central nervous system cells(mainly microglia)to trigger a secondary neuroimmune *** review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic *** found that,during ischemic stroke,T cells and microglia demonstrate a more pronounced synergistic ***1,Th17,and M1 microglia can co-secrete proinflammatory factors,such as interferon-γ,tumor necrosis factor-α,and interleukin-1β,to promote neuroinflammation and exacerbate brain ***2,Treg,and M2 microglia jointly secrete anti-inflammatory factors,such as interleukin-4,interleukin-10,and transforming growth factor-β,to inhibit the progression of neuroinflammation,as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain *** interactions between microglia and T cells influence the direction of the subsequent neuroinflammation,which in turn determines the prognosis of ischemic stroke *** trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic ***,such studies have been relatively infrequent,and clinical experience is still *** summary,in ischemic stroke,T cell subsets and activated micro

关键词： brain immune inflammation interaction ischemic stroke mechanism microglia neuron secondary injury T cells

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Preparation of silver nanoparticles through the reduction of straw-extracted lignin and its antibacterial hydrogel

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 504-514页

作者： Lou Zhang Shuo Li Fu Tang Jingkai Zhang Yuetong Kang Hean Zhang Lidong Li State Key Laboratory for Advanced Metals and Materials School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial ***,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water *** this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing *** analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag *** surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their *** the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite *** inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag *** prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.

关键词： silver nanoparticles hydrogel straw extraction antibacterial

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SensFL:Privacy-Preserving Vertical Federated Learning with Sensitive Regularization

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 385-404页

作者： Chongzhen Zhang Zhichen Liu Xiangrui Xu Fuqiang Hu Jiao Dai Baigen Cai Wei Wang School of Automation and Intelligence Beijing Jiaotong UniversityBeijing100044China Shuohuang Railway Development Co. Ltd.National Energy GroupCangzhou062350China beijing Key Laboratory of Security and Privacy in Intelligent Transportation School of Computer Science and TechnologyBeijing Jiaotong UniversityBeijing100044China

In the realm of Intelligent Railway Transportation Systems,effective multi-party collaboration is crucial due to concerns over privacy and data *** Federated Learning(VFL)has emerged as a promising approach to facilitate such collaboration,allowing diverse entities to collectively enhance machine learning models without the need to share sensitive training ***,existing works have highlighted VFL’s susceptibility to privacy inference attacks,where an honest but curious server could potentially reconstruct a client’s raw data from embeddings uploaded by the *** vulnerability poses a significant threat to VFL-based intelligent railway transportation *** this paper,we introduce SensFL,a novel privacy-enhancing method to against privacy inference attacks in ***,SensFL integrates regularization of the sensitivity of embeddings to the original data into the model training process,effectively limiting the information contained in shared *** reducing the sensitivity of embeddings to the original data,SensFL can effectively resist reverse privacy attacks and prevent the reconstruction of the original data from the *** experiments were conducted on four distinct datasets and three different models to demonstrate the efficacy of *** results show that SensFL can effectively mitigate privacy inference attacks while maintaining the accuracy of the primary learning *** results underscore SensFL’s potential to advance privacy protection technologies within VFL-based intelligent railway systems,addressing critical security concerns in collaborative learning environments.

关键词： Vertical federated learning privacy defenses

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A new type of damper with friction-variable characteristics

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Earthquake Engineering and Engineering Vibration 2009年第4期8卷 507-520页

作者： Zhou Xiyuan Peng Lingyun beijing Key Lab of Earthquake Engineering and Structural Retrofit beijing University of Technology beijing 100124. china

Professor T. T. Soong is one of the early pioneers in field of earthquake responsc control of structures. A new type of smart damper, which is based on an Energy Dissipating Restraint （EDR）, is presented in this paper. The EDR by Nims and Kelly, which has a triangle hysteretic loop, behaves like an active variable stiffness system （AVS） and possesses the basic characteristics of a linear viscous damper but has difficulty in capturing the output and large stroke simultaneously needed for practical applicataions in engineering structures. In order to overcome this limitation, the friction surface in the original Sumitomo EDR is divided into two parts with low and high friction coefficients in this paper. The results of finite element analysis studies show that the new type of smart friction damper enables large friction force in proportion to relative displacement between two ends of the damper and has a large allowable displacement to fit the demands of engineering applications. However, unlike the EDR by Nims and Kelly, this type of friction variable damper cannot self re-center. However, the lateral stiffness can be used to restore the structure. The nonlinear time history analysis of earthquake response for a structure equipped with the proposed friction variable dampers was carried out using the IDARC computer program. The results indicate that the proposed damper can successfully reduce the earthquake response of a structure.

关键词： friction variable damper energy dissipation restraint hysteretic performance finite element analysis nonlinear time history analysis

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Distributed Estimation and Analysis of Precipitation Recharge Coefficient in Strongly-exploited beijing Plain Area, china

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Chinese Geographical Science 2017年第1期27卷 88-96页

作者： PAN Yun GONG Huili SUN Ying WANG Xinjuan DING Fei College of Resources Environment and Tourism Capital Normal University Beijing 100048 China beijing Institute of Hydrogeology and Engineering Geology Beijing 100195 China College of Architecture and Civil Engineering Beijing University of Technology Beijing 100124 China

The precipitation recharge coefficient(PRC), representing the amount of groundwater recharge from precipitation, is an important parameter for groundwater resources evaluation and numerical simulation. It was usually obtained from empirical knowledge and site experiments in the 1980 s. However, the environmental settings have been greatly modified from that time due to land use change and groundwater over-pumping, especially in the beijing plain area(BPA). This paper aims to estimate and analyze PRC of BPA with the distributed hydrological model and GIS for the year 2011 with similar annual precipitation as long-term mean. It is found that the recharge from vertical(precipitation + irrigation) and precipitation is 291.0 mm/yr and 233.7 mm/yr, respectively, which accounts for 38.6% and 36.6% of corresponding input water. The regional mean PRC is 0.366, which is a little different from the traditional map. However, it has a spatial variation ranging from –7.0% to 17.5% for various sub-regions. Since the vadose zone is now much thicker than the evaporation extinction depth, the land cover is regarded as the major dynamic factor that causes the variation of PRC in this area due to the difference of evapotranspiration rates. It is suggested that the negative impact of reforestation on groundwater quantity within BPA should be well investigated, because the PRC beneath forestland is the smallest among all land cover types.

关键词： groundwater recharge distributed hydrological model land cover geographic information systems

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A Novel Model for Describing Rail Weld Irregularities and Predicting Wheel-Rail Forces Using a Machine Learning Approach

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 555-577页

作者： Linlin Sun Zihui Wang Shukun Cui Ziquan Yan Weiping Hu Qingchun Meng State Key Laboratory of High-Speed Railway Track System China Academy of Railway Sciences Corporation LimitedBeijing100081China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing100081China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed *** can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and *** researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry ***,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric *** this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from beijing to *** vertical dynamic forces in the time and frequency domains were compared under different running *** forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed ***,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is *** results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the *** ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.

关键词： Rail weld irregularity high-speed railway vehicle-track coupled dynamics wheel/rail dynamic vertical force artificial neural networks

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