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Atomistic study of inverse size effect induced by interfacial plasticity in pearlitic multi-principal element alloy

Rare Metals 2024年第7期43卷 3341-3355页

作者： Chen Yang Qiao-Sheng Xia Cun-Hong yin dong-Peng Hua College of Mechanical Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Advanced Manufacturing Technology Ministry of EducationGuizhou UniversityGuiyang 550025China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China

Owing to the fine nano-laminated structure,the pearlitic multi-principal element alloy(PMPEA) exhibits excellent mechanical and tribological ***,the incomplete understanding of the size effect of its lamella thickness and the unclear understanding of the plasticity-interface interaction mechanism limit further optimization of *** this study,the FeCoNi/Ni_3Ti interface-mediated plastic deformation behavior in PMPEA and the variation of mechanical and tribological properties with lamella thickness within the nanoscale range using molecular dynamics(MD) simulation were *** results indicate that the mechanical and tribological properties of the PMPEA with lamella thicknesses below 10 nm have a significant inverse size effect,i.e.,the smaller the lamella thickness,the weaker the *** is because the plastic carrier-interface interaction mechanism changes from a strengthening mechanism that hinders dislocations to a weakening mechanism that promotes dislocations with the decreases in the lamella thickness,and the weakening effect becomes more pronounced as the lamella thickness decreases and the number of interfaces *** particular,the deformation behavior of Ni_3Ti lamellae changes from crystal-like to amorphous-like with decreasing ***,in the sample with larger lamella thickness,the occurrence of hierarchical slips in the body-centered cubic(BCC) phase due to the multiprincipal elements effect can better alleviate the stress concentration caused by the dislocation accumulation at the interface,so that the phase interface exhibits outstanding load-bearing *** the dislocation pattern in BCC phase shows a firm high-density cell,which makes the substrate exhibit a stable tribological response.

关键词： Multi-principal element alloy Nano-laminated structure Molecular dynamics simulation Nanoindentation and nanoscratch

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Monotonic mechanical behaviour of compacted completely decomposed granite with various inclusion levels of incineration bottom ash

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 670-679页

作者： Han-Lin WANG Cheng-Shuang yin Qian-Yi ZHANG Qi-Wei LIU Zhen-Yu yin dong-Xing XUAN Askar KHASANOV Research Center for Advanced Underground Space Technologies of Hunan University Changsha 410082China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan UniversityChangsha 410082China College of Civil Engineering Hunan UniversityChangsha 410082China School of Civil Engineering Zhengzhou UniversityZhengzhou 450001China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Department of Applied and Theoretical Mechanics Samarkand State UniversitySamarkandUzbekistan

1 Introduction Completely decomposed granite(CDG)is widely distributed in South China(Xu et al.,2022;Wang et al.,2023).The parent granite rock mass gradually loses features during the weathering process,and thus needs to be reinforced when used(Lan et al.,2003;Dassekpo et al.,2017;Alamanis et al.,2021).On the other hand,considering the huge demand for construction materials and limited natural resources,it is increasingly important to fully utilize solid waste(Gruhler et al.,2019;Anagnostopoulos et al.,2020;Jiang et al.,2022,2023a,2023b).With high strength and environment-friendly characteristics,incineration bottom ash(IBA)seems to be a suitable reinforcement material for CDG(Ahmed and Khalid,2011;Alhassan and Tankó,2012;Toraldo et al.,2013;Lynn et al.,2017;Xuan et al.,2018;Tang et al.,2020).

关键词： incineration behaviour utilize

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Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

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High Voltage 2024年第1期9卷 252-265页

作者： Minghai dong Hui Li Shan yin Kye Yak See yingzhe Wu Xiong Xin School of Aeronautics&Astronautics University of Electronic Science and Technology of ChinaChengduChina School of Electrical&Electronic Engineering Nanyang Technological UniversitySingaporeSingapore School of Automation Engineering University of Electronic Science and Technology of ChinaChengduChina Innoscience(Shenzhen)Semiconductor Co.Ltd. ShenzhenChina

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power *** bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant ***,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)*** oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency *** authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be *** facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with *** relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH ***,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

关键词： power resonant high

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Strengthening mechanism and forming control of linear friction welded GH4169 alloy joints

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Chinese Journal of Aeronautics 2024年第4期37卷 609-626页

作者： Yu SU Xiawei YANG Tingxi MENG Xinyuan HE dong WU Wenya LI Shuo yin State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Friction Welding Technologies School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Manufacturing and Biomedical EngineeringParsons BuildingTrinity College DublinThe University of DublinDublin 2Ireland

Numerical simulation and experimental research on Linear Friction Welding(LFW) for GH4169 superalloy were carried out. Based on the joint microstructure and mechanical properties,a suitable welding process was determined, which provided an important theoretical basis for the manufacture and repair of aeroengine components such as the superalloy blisk. The results show that the joint strain rate gradually increases with the increase of welding frequency, and the deformation resistance of the thermoplastic metal increases in the welding process, resulting in the interface thermoplastic metal not being extruded in time to form a flash, so the joint shortening amount gradually decreases. The thermoplastic metal in the center of the welding surface is kept at high welding temperature for a long time, resulting in the decrease of the joint strength. The microhardness of the joint shows a “W” distribution perpendicular to the weld, and most of the joints break in the Thermo-Mechanically Affected Zone(TMAZ) with high tensile strength and low *** the welding area is increased without changing the aspect ratio of the welding surface, the interface peak temperature increases gradually, and the joint shortening amount decreases with the increase of the welding interface size.

关键词： Linear Friction Welding(LFW) Microstructure Mechanical properties Numerical simulation Joint shortening amount

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Self-supervised recalibration network for person re-identification

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Defence Technology（防务技术） 2024年第1期31卷 163-178页

作者： Shaoqi Hou Zhiming Wang Zhihua dong Ye Li Zhiguo Wang Guangqiang yin Xinzhong Wang Shenzhen Institute of Information Technology Shenzhen518172China University of Electronic Science and Technology of China Chengdu611731China Kash Institute of Electronics and Information Industry Kashi844099China

The attention mechanism can extract salient features in images,which has been proved to be effective in improving the performance of person re-identification(Re-ID).However,most of the existing attention modules have the following two shortcomings:On the one hand,they mostly use global average pooling to generate context descriptors,without highlighting the guiding role of salient information on descriptor generation,resulting in insufficient ability of the final generated attention mask representation;On the other hand,the design of most attention modules is complicated,which greatly increases the computational cost of the *** solve these problems,this paper proposes an attention module called self-supervised recalibration(SR)block,which introduces both global and local information through adaptive weighted fusion to generate a more refined attention *** particular,a special"Squeeze-Excitation"(SE)unit is designed in the SR block to further process the generated intermediate masks,both for nonlinearizations of the features and for constraint of the resulting computation by controlling the number of ***,we combine the most commonly used Res Net-50 to construct the instantiation model of the SR block,and verify its effectiveness on multiple Re-ID datasets,especially the mean Average Precision(m AP)on the Occluded-Duke dataset exceeds the state-of-the-art(SOTA)algorithm by 4.49%.

关键词： Person re-identification Attention mechanism Global information Local information Adaptive weighted fusion

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Ultrahard X-ray multifunctional application beamline at the SSRF

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Nuclear Science and Techniques 2024年第6期35卷 14-25页

作者： Ke Yang Zhao-Hui dong Chun-yin Zhou Zi-Long Zhao dong-Xu Liang Sai-Chao Cao Ai-Guo Li Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China

The ultrahard X-ray multifunctional application beamline(BL12SW)is a phase-II beamline project at the Shanghai Syn-chrotron Radiation *** primary X-ray techniques used at the beamline are high-energy X-ray diffraction and imaging using white and monochromatic *** main scientific objectives of ultrahard X-ray beamlines are focused on two research *** is the study of the structural properties of Earth’s interior and new materials under extreme high-temperature and high-pressure conditions,and the other is the characterization of materials and processes in near-real service *** beamline utilizes a superconducting wiggler as the light source,with two diamond windows and SiC discs to filter out low-energy light(primarily below 30 keV)and a Cu filter assembly to control the thermal load entering the subsequent optical *** beamline is equipped with dual *** first was a meridional bending Laue monochromator cooled by liquid nitrogen,achieving a full-energy coverage of 30-162 *** second was a sagittal bending Laue monochromator installed in an external building,providing a focused beam in the horizontal direction with an energy range of 60-120 *** were four experimental hutches:two large-volume press experimental hutches(LVP1 and LVP2)and two engineering material experimental hutches(ENG1 and ENG2).Each hutch was equipped with various near-real service conditions to satisfy different *** example,LVP1 and LVP2 were equipped with a 200-ton DDIA press and a 2000-ton dual-mode(DDIA and Kawai)press,***1 and ENG2 provide in situ tensile,creep,and fatigue tests as well as high-temperature *** June 2023,the BL12SW has been in trial *** is expected to officially open to users by early 2024.

关键词： Shanghai Synchrotron Radiation Facility Ultrahard X-ray High energy diffraction High energy imaging Engineering materials Earth science

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A 10-yr Rainfall and Cloud-to-Ground Lightning Climatology over Coastal and Inland Regions of Guangdong,China during the Pre-Summer Rainy Season

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Journal of Meteorological Research 2024年第3期38卷 469-488页

作者： Yuqing RUAN Rudi XIA Xinghua BAO dong ZHENG Yan SHEN Jinfang yin State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing210044China National Meteorological Information Centre China Meteorological AdministrationBeijing100081China

A comparative analysis of the spatiotemporal distribution characteristics of rainfall and lightning in coastal and inland areas of Guangdong Province of China during the pre-summer rainy season(PSRS)from 2008 to 2017 reveals distinct *** the inland target region(ITR),rainfall is concentrated in the central and eastern mountainous *** exhibits a bimodal diurnal variation,with peaks in the afternoon and *** afternoon peak becomes more pronounced during the post-monsoon-onset period because of the increased rainfall ***,in the coastal target region(CTR),rainfall concentrates around mountainous ***,CTR’s rainfall is weaker than ITR’s during the pre-monsoon-onset period,primarily associated with the lower-level moisture outflow in CTR,but it strengthens significantly during the post-monsoon-onset period owing to enhanced moisture ***’s diurnal rainfall variation transitions from bimodal to a single broad peak during the post-monsoon-onset period,influenced by changes in both rainfall frequency and *** contrast to rainfall,the spatiotemporal distribution of lightning centers remains relatively stable during the *** strongest center is located over ITR’s plains west of the rainfall center,with a secondary center in the western plains of *** activity significantly increases during the post-monsoon-onset period,particularly in ITR,primarily because of the increased lightning *** diurnal lightning flash density and lightning hours show a single afternoon peak in the two target regions,and the timing of the peak in ITR is approximately two hours later than in *** circulation analysis indicates that during early morning,the lower atmosphere is nearly neutral in *** advected warm,moist,unstable airflow,combined with topography,favors convection *** the afternoon,solar radiation increases thermal instability,further enhancing the convection frequency and in

关键词： rainfall lightning spatiotemporal distribution diurnal variation pre-summer rainy season

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Forecast of cosmological constraints with superluminous supernovae from the Chinese Space Station Telescope

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Science China(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 132-142页

作者： Xuan-dong Jia Jian-Ping Hu Fa-yin Wang Zi-Gao Dai School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Department of Astronomy University of Science and Technology of China

Superluminous supernovae（SLSNe） are a class of intense celestial events that can be standardized for measuring cosmological parameters, bridging the gap between type Ia supernovae and the cosmic microwave background. In this work, we discuss the cosmological applications of SLSNe from the Chinese Space Station Telescope（CSST）. Our estimation suggests that SLSNe rate is biased tracing the cosmic star formation rate, exhibiting a factor of （1 + z）1.2. We futher predict that CSST is poised to observe ～360 SLSNe in the 10 square degrees ultra-deep field survey within a span of 2.5 years. A stringent constraint on cosmological parameters can be derived from their peak-color relationship. CSST is anticipated to uncover a substantial number of SLSNe, contributing to a deeper understanding of their central engines and shedding light on the nature of dark energy at high redshifts.

关键词： supernovae cosmology cosmological constant

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Effect of linear friction welding process on microstructure evolution,mechanical properties and corrosion behavior of GH4169 superalloy

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Chinese Journal of Aeronautics 2024年第6期37卷 504-520页

作者： Yu SU Xiawei YANG Tingxi MENG dong WU Rui XU Haiyu XU Wenya LI Shuo yin State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Manufacturing&Biomedical EngineeringParsons BuildingTrinity College DublinThe University of DublinDublin 2Ireland

Linear Friction Welding(LFW)technology was used to realize the welding of GH4169 superalloy,and the effect of welding parameters on the microstructure,mechanical properties and corrosion behavior of the joint was *** results show that there is a positive correlation between the weld hardness and the tensile *** the gradual increase of heat input and welding pressure,the joint quality is gradually improved,but the heat affected zone is not significantly *** smaller the grain size of the weld,the higher the strength and plasticity of the *** the increase of the joint shortening amount,the corrosion resistance of the weld first gradually ***,when the shortening reaches a certain level,the corrosion resistance of the joint becomes little *** the increase of solution temperature,the corrosion current density increases and the polarization impedance *** higher the corrosion temperature,the worse the corrosion resistance of the *** is no significant correlation between the joint strength and the corrosion *** corrosion resistance of the joint can be enhanced without changing the joint mechanical properties by reducing the welding frequency and amplitude or increasing the welding pressure.

关键词： Linear Friction Welding(LFW) GH4169 superalloy Microstructure Mechanical properties Corrosion behavior

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A novel lead-free relaxor with endotaxial nanostructures for capacitive energy storage

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SusMat 2024年第1期4卷 116-125页

作者： Xiaoyan dong Tengfei Hu XiaojunWu Jie yin Zhengqian Fu Jiagang Wu College of Materials Science and Engineering Sichuan UniversityChengduP.R.China Analysis and Testing Center for Inorganic Materials Shanghai Institute of CeramicsChinese Academy of SciencesShanghaiP.R.China

Dielectric capacitors with a fast charging/discharging rate,high power density,and long-term stability are essential components in modern electrical ***,miniaturizing and integrating capacitors face a persistent challenge in improving their energy density(W_(rec))to satisfy the specifications of advanced electronic systems and *** this work,leveraging phase-field simulations,we judiciously designed a novel lead-free relaxor ferroelectric material for enhanced energy storage performance,featuring flexible distributed weakly polar endotaxial nanostructures(ENs)embedded within a strongly polar fluctuation *** matrix contributes to substantially enhanced polarization under an external electric field,and the randomly dispersed ENs effectively optimize breakdown phase proportion and provide a strong restoring force,which are advantageous in bolstering breakdown strength and minimizing ***,this relaxor ferroelectric system incorporating ENs achieves an exceptionally high W_(rec)value of 10.3 J/cm^(3),accompanied by a large energy storage efficiency(η)of 85.4%.This work introduces a promising avenue for designing new relaxor materials capable of capacitive energy storage with exceptional performance characteristics.

关键词： endotaxial nanostructure energy storage lead-free relaxor ferroelectric

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