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Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy:Effect of ferric ion irradiation

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journal of Materials Science & Technology 2023年第36期167卷 228-236页

作者： Y.Zhang C.W.Li j.L.jiang j.f.gu H.Wang Y.D.jia G.Wang X.G.An Q.Wang j.Lu Institute of Materials Shanghai UniversityShanghai 200072China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanical Engineering City University of Hong KongKowloonSARChina Science and Technology on Reactor fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610041China Interdisciplinary Materials Research Center Institute for Advanced StudyChengdu UniversityChengdu610106China

Spherical nanoindentation of an iron-chromium-aluminum alloy was conducted to study the effect of ferric-ion(fe 3+)irradiation on the time-dependent plasticity behavior in the surface layers of this *** was observed that the initiation of plasticity by the appearance of displacement burst or“pop-in”event occurred after a period of waiting time in the apparent elastic regime and that fe^(3+)irradiation at 360°C and up to∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced *** the experimental data,an activation volume and activation energy were extracted for the delayed *** results show that fe^(3+)-irradiation significantly reduced its acti-vation volume from∼3.05 b 3 to∼1.75 b 3(where b=Burgers vector),but slightly increased its activation energy from∼0.65 to∼0.71 *** the other hand,high-resolution scanning transmission electron mi-croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the(100)habit plane that can serve as the nucleation site of a100dislocation loop while elim-inating the pre-existing ***,it is indicated that heterogeneous nucleation of the dislocation loop was predominant in the delayed plasticity initiation of this alloy and that the nucleation of the interstitial-type dislocation loop was involved due to fe^(3+)-irradiation.

关键词： Spherical nanoindentation Delayed plasticity feCrAl alloy fe^(3+)-irradiation

Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

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journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.H.Zhang H.Li Z.W.Yang X.Liu Q.f.gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of High-Performance Precision forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace field due to its wide transformation *** application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to ***-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SMA ***,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were *** results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,*** stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced ***{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then ***ε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase ofε_(re)^(T)can be attributed to the formation of new SIMVs,the further growth of existing SIMVs,and the recoverable(001)compound *** the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite *** effe

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Self-attention guidance Based Crowd Localization and Counting

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Machine Intelligence Research 2024年第5期21卷 966-982页

作者： Zhouzhou Ma guanghua gu Wenrui Zhao School of Information Science and Engineering Yanshan UniversityQinhuangdao066000China Hebei Key Laboratory of Information Transmission and Signal Processing Qinhuangdao066000China

Most existing studies on crowd analysis are limited to the level of counting,which cannot provide the exact location of *** paper proposes a self-attention guidance based crowd localization and counting network(SA-CLCN),which can simultaneously locate and count *** take the form of object detection,using the original point annotations of crowd datasets as supervision to train the ***,the center point coordinate of each head as well as the number of crowds are ***,to cope with the spatial and positional variations of the crowd,the proposed method introduces transformer to construct a globallocal feature extractor(GLfE)together with the convolutional *** establishes the near-to-far dependency between elements so that the global context and local detail features of the crowd image can be extracted ***,this paper designs a pyramid feature fusion module(PffM)to fuse the global and local information from high level to low level to obtain a multiscale feature *** downstream tasks,this paper predicts candidate point offsets and confidence scores by a simple regression header and classification *** addition,the Hungarian algorithm is used to match the predicted point set and the labelled point set to facilitate the calculation of *** proposed network avoids the errors or higher costs associated with using traditional density maps or bounding box ***,we have conducted extensive experiments on several crowd datasets,and the proposed method has produced competitive results in both counting and localization.

关键词： Crowd localization crowd counting transformer point supervision object detection

Generation of polarized electron beams through self-injection in the interaction of a laser with a pre-polarized plasma

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High Power Laser Science and Engineering 2024年第3期12卷 62-68页

作者： L.R.Yin X.f.Li Y.j.gu N.Cao Q.Kong M.Büscher S.M.Weng M.Chen Z.M.Sheng Key Laboratory of Nuclear Physics and Ion-beam Application(MoE) Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan UniversityShanghaiChina State Key Laboratory of High field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghaiChina SANKEN(Institute of Scientific and Industrial Research) Osaka UniversityOsakaJapan Sichuan Research Institute Shanghai Jiao Tong UniversityChengduChina Peter Grünberg Institut(PGI-6) Forschungszentrum JülichJülichGermany Institut für Laser-und Plasmaphysik Heinrich-Heine-Universität DüsseldorfDüsseldorfGermany Key Laboratory for Laser Plasmas(MoE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IfSA Shanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

Polarized electron beam production via laser wakefield acceleration in pre-polarized plasma is investigated by particlein-cell *** evolution of the electron beam polarization is studied based on the Thomas±Bargmann±Michel±Telegdi equation for the transverse and longitudinal self-injection,and the depolarization process is found to be influenced by the injection *** the case of transverse self-injection,as found typically in the bubble regime,the spin precession of the accelerated electrons is mainly influenced by the ***,in the case of longitudinal injection in the quasi-1D regime(for example,*** et al.,***.110,135002(2013)),the direction of electron spin oscillates in the laser *** the electrons move around the laser axis,the net influence of the laser field is nearly zero and the contribution of the wakefield can be ***,an ultra-short electron beam with polarization of 99%can be obtained using longitudinal self-injection.

关键词： laser wakefield acceleration longitudinal self-injection particle-in-cell simulation polarized electron beam

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Grading of products utilizing bamboo as a substitute for plastic based on environmental effects

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Science China Earth Sciences 2024年第9期67卷 2989-2998页

作者： Meng ZHANG guomo ZHOU Lei gu Wenshuo WANG College of forestry Beijing Forestry UniversityBeijing 100083China Key Laboratory of Carbon Cycling in forest Ecosystems and Carbon Sequestration of Zhejiang Province Zhejiang A&F UniversityHangzhou 311300China

To achieve sustainable development goals,mitigate plastic pollution,and promote eco-friendly products,it is crucial to identify key products in the bamboo as a substitute for plastic(BSP)industry and assess their environmental *** study proposed a novel evaluation method for the environmental effect of bamboo as a substitute for plastic(EBSP).It focused on the contributions of BSP products in reducing plastic pollution and greenhouse gas *** established a set of EBSP evaluation indicators and developed a grading model,evaluating 30 typical BSP products across six *** results showed that the EBSP evaluation model,based on the emission reduction rate of substitution(ERRS),substitution rate of material(SRM),and product renewal ratio(PRR),can accurately quantify the environmental benefits of BSP *** model has successfully facilitated precise quantification of the EBSP and established a rational and effective grading system for BSP *** results also demonstrated that the average EBSP ranking across the six categories of BSP products,in descending order,is:disposable bamboo products,bamboo household goods,bamboo packaging products,bamboo engineering materials,bamboo furniture products,and bamboo craft ***,disposable bamboo products scored an EBSP 1.96 times the overall average,indicating significant environmental *** PRR emerged as a critical factor influencing *** BSP products with the same lifespan,those with higher substitution emission reduction efficiency offered more pronounced environmental ***,the BSP industry should strategically prioritize disposable bamboo products,such as bamboo toothbrushes,cutlery,and lunch *** products should be the primary focus of policy support and central to efforts in product development,design innovation,and market promotion.

关键词： Bamboo as a substitute for plastic Bamboo products Substitution emission reduction Environmental benefits Gradingevaluation

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2019新型冠状病毒肺炎(COVID-19)连续RT-PCR结果与胸部CT成像的时间关系及连续CT改变：对中国155例病人的描述性研究

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国际医学放射学杂志 2021年第3期44卷 363-363页

作者： j.f.gu L.Yang T.Li Y.Liu j.Zhang K.j.Ning 卢明明

摘要目的探讨CT在早期发现新型冠状病毒肺炎(COVID-19)中的作用以及COVID-19病人的病程中连续CT改变。方法回顾性收集2020年1月21日—2月18日所

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Cell Consistency Evaluation Method Based on Multiple Unsupervised Learning Algorithms

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Big Data Mining and Analytics 2024年第1期7卷 42-54页

作者： jiang Chang Xianglong gu jieyun Wu Debu Zhang Stellantis China Technology Center Shanghai 200233China

Unsupervised learning algorithms can effectively solve sample *** address battery consistency anomalies in new energy vehicles,we adopt a variety of unsupervised learning algorithms to evaluate and predict the battery consistency of three vehicles using charging fragment data from actual operating *** extract battery-related features,such as the mean of maximum difference,standard deviation,and entropy of batteries and then apply principal component analysis to reduce the dimensionality and record the amount of preserved *** then build models through a collection of unsupervised learning algorithms for the anomaly detection of cell consistency *** also determine whether unsupervised and supervised learning algorithms can address the battery consistency problem and document the parameter tuning *** addition,we compare the prediction effectiveness of charging and discharging features modeled individually and in combination,determine the choice of charging and discharging features to be modeled in combination,and visualize the multidimensional data for fault *** results show that the unsupervised learning algorithm is effective in visualizing and predicting vehicle core conformance faults,and can accurately predict faults in real ***“distance+boxplot”algorithm shows the best performance with a prediction accuracy of 80%,a recall rate of 100%,and an f1 of *** proposed approach can be applied to monitor battery consistency faults in real time and reduce the possibility of disasters arising from consistency faults.

关键词： battery consistency charging segment data unsupervised learning

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

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Nano Research 2024年第3期17卷 1552-1563页

作者： jinrui Ye Zhongbao Wang Qin Lei Lei Sun jinfeng gu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Tangshan Research Institute Beijing Institute of TechnologyTangshan 063000China School of Materials Science and Engineering Shenyang Jianzhu UniversityShenyang 110168China Department of Stomatology PLA Strategic Support Force Characteristic Medical CenterBeijing 100101China Beijing Electromechanical Engineering Research Institute Beijing 100074China

Structural energy storage composites present advantages in simultaneously achieving structural strength and electrochemical *** of carbon fiber electrodes and resin structural electrolytes in energy storage composite poses challenges in maintaining good mechanical and electrochemical properties at reasonable cost and ***,we report a simple method to fabricate structural supercapacitor using carbon fiber electrodes(modified by Ni-layered double hydroxide(Ni-LDH)and in-situ growth of Co-metal-organic framework(Co-MOf)in a two-step process denoted as Co-MOf/Ni-LDH@Cf)and bicontinuous-phase epoxy resin-based structural ***-MOf/Ni-LDH@Cf as electrode material exhibits improved specific capacity(42.45 f·g^(-1))and cycle performance(93.3%capacity retention after 1000 cycles)in a three-electrode *** bicontinuous-phase epoxy resin-based structural electrolyte exhibits an ionic conductivity of 3.27×10^(-4) S·cm^(-1).The fabricated Co-MOf/Ni-LDH@Cf/SPE-50 structural supercapacitor has an energy density of 3.21 Wh·kg^(-1) at a power density of 42.25 W·kg^(-1),whilst maintaining tensile strength and modulus of 334.6 MPa and 25.2 *** results show practical potential of employing modified commercial carbon fiber electrodes and epoxy resin-based structural electrolytes in structural energy storage applications.

关键词： carbon fiber electrode structural electrolyte structural energy storage composites supercapacitor

Taxonomic dependency and spatial heterogeneity in assembly mechanisms of bacteria across complex coastal waters

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Ecological Processes 2024年第1期13卷 80-97页

作者： Huizhen Yan Dandan Lin Gaoke gu Yujie Huang Xuya Hu Zhenhao Yu Dandi Hou Demin Zhang Barbara j.Campbell Kai Wang State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products School of Marine SciencesNingbo University Key Laboratory of Marine Biotechnology of Zhejiang Province School of Marine Sciences Ningbo University Department of Biological Sciences Clemson University

Background Understanding community assembly mechanisms across taxa and space is fundamental for microbial ecology. However, the variability and determinants of assembly processes over taxa and space remain unclear. Here, we investigated taxonomic dependency and spatial heterogeneity in bacterial assembly mechanisms across coastal waters in the East China Sea using neutral and null models with customized visualization *** Overall, bacterial assembly mechanisms varied across broad taxonomic groups(phyla and proteobacterial classes) and space at the regional scale. A determinism–stochasticity balanced mechanism governed total bacterial assembly, while taxonomic dependency existed in assembly mechanisms and ecological processes. Among community ecological features, niche breadth and negative-to-positive cohesion ratio were strongly associated with the determinism-to-stochasticity ratio of bacterial groups. Bacterial assembly mechanisms commonly exhibited spatial heterogeneity, the extent and determinants of which varied across taxonomic groups. Spatial assembly of total bacteria was directly driven by many environmental factors and potential interactions between taxa, but not directly by geographic factors. Overall, the bacterial groups with higher spatial heterogeneity in assembly mechanisms were more related to environmental and/or geographic factors(except Bacteroidetes), while those with lower heterogeneity were more related to ecological *** Our results confirm the pervasiveness of taxonomic dependency and spatial heterogeneity in bacterial assembly, providing a finer understanding about regulation across complex coastal waters.

关键词： Bacterioplankton Assembly mechanism Niche breadth Null model Environmental gradient Biogeography