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Seynergistic effect of Mo and Zr additions on microstructure and mechanical properties of Nb-Ti-Si-based alloys additively manufactured by laser directed energy deposition

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Journal of Materials Science & Technology 2022年第8期103卷 84-97页

作者： yunlong Li Xin Lin Yunlong Hu Jun Yu Junguo Zhao Hongbiao Dong Weidong huang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design MIIT ChinaNorthwestern Polytechnical UniversityXi’an 710072China School of Engineering University of LeicesterLE17RHUK

The synergistic effect of Mo and Zr additions on microstructure evolution,room-temperature fracture toughness and microhardness of Nb-22Ti-15Si-xMo-yZr(x=4,8,y=3,6)alloys manufactured by laser directed energy deposited(L-DED)have been investigated.The major phases in as-deposited 4Mo-3Zr alloy are Nb solid solution(Nbss),Nb_(3)Si andγ-Nb_(5)Si_(3).The Nb_(3)Si phases disappear with increasing Mo content to 8 at.%or increasing Zr content to 6%.γ-Nb_(5)Si_(3) precipitates formed in the Nbss of as-deposited xMo-yZr alloys due to the cyclic re-heating,and theγ-Nb_(5)Si_(3) precipitates and Nbss matrix exhibits orientation relationship(OR)of[001]Nbss//[1112]γand(110)Nbss//(0110)γin as-deposited 4Mo-6Zr alloy.The microstructure of xMo-yZr alloys became relative homogeneity and the Nbss matrix showed the better continuity after the heat treatment(1400°C/30 h).The Nb_(3)Si phase has transformed into Nbss andαNb_(5)Si_(3) with the OR have been determined as{100}Nbss//{100}αand{111}Nbss//{111}αin the heat-treated 4Mo-3Zr alloy.When Mo content increase to 8at.%,a part ofγ-Nb_(5)Si_(3) phase also transformed into theα-Nb_(5)Si_(3) phase with the OR have been determined as{1120}γ//{110}αand{1010}γ//{111}αafter heat treatment.Among the as-deposited alloys,the 4Mo-6Zr alloy has the highest fracture toughness KQ with the lowest hardness.The average KQ of 4Mo-6Zr and 8Mo-6Zr alloys increased by 28%and 30%after the heat treatment,and reached 13.61 and 11.43 MPa·m^(1/2),respectively.The hardness of Nb-22Ti-15Si-xMoyZr alloys is significantly decreased after the heat treatment.

关键词： alloys microstructure toughness

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Variability of the Pacific subtropical cells under global warming in CMIP6 models

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Journal of Oceanology and Limnology 2024年第1期42卷 24-40页

作者： Xue HAN Junqiao FENG yunlong LU Dunxin hu Key Laboratory of Ocean Circulation and Waves Chinese Academy of SciencesQingdao 266071China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Laboratory for Ocean Dynamics and Climate Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

The Pacific subtropical cells(STCs)are shallow meridional overturning circulations connecting the tropics and subtropics,and are assumed to be an important driver of the tropical Pacific decadal variability.The variability of STCs under global warming is investigated using multimodal outputs from the latest phase of the Coupled Model Inter-comparison Project(CMIP6)and ocean reanalysis products.Firstly,the volume transport diagnostic analysis is employed to evaluate how coupled models and ocean reanalysis products reproduce interior STC transport.The variation of heat transport by the interior STC under the high-emissions warming scenarios is also analyzed.The results show that the multimodal-mean linear trends of the interior STC transport along 9°S and 9°N are-0.02 Sv/a and 0.04 Sv/a under global warming,respectively,which is mainly due to the combined effect of the strengthened upper oceanic stratification and the weakening of wind field.There is a compensation relationship between the interior STC and the western boundary transport in the future climate,and the compensation relationship of 9°S is more significant than that of 9°N.In addition,compared with ocean reanalysis products,the coupled models tend to underestimate the variability of the interior STC transport convergence,and thus may lose some sea surface temperature(SST)driving force,which may be the reason for the low STC-SST correlation simulated by the model.The future scenario simulation shows that the heat transport of interior STC is weakened under global warming,with a general agreement across models.

关键词： interior subtropical cell(STC) global warming Coupled Model Inter-comparison Project(CMIP6) western boundary transport

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CASIA-Iris-Africa:A Large-scale African Iris Image Database

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Machine Intelligence Research 2024年第2期21卷 383-399页

作者： Jawad Muhammad yunlong Wang Junxing hu Kunbo Zhang Zhenan Sun School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China Center for Research on Intelligent Perception and Computing National Laboratory of Pattern RecognitionInstitute of AutomationChinese Academy of SciencesBeijing 100190China

Iris biometrics is a phenotypic biometric trait that has proven to be agnostic to human natural physiological changes.Research on iris biometrics has progressed tremendously,partly due to publicly available iris databases.Various databases have been available to researchers that address pressing iris biometric challenges such as constraint,mobile,multispectral,synthetics,long-distance,contact lenses,liveness detection,etc.However,these databases mostly contain subjects of Caucasian and Asian docents with very few Africans.Despite many investigative studies on racial bias in face biometrics,very few studies on iris biometrics have been published,mainly due to the lack of racially diverse large-scale databases containing sufficient iris samples of Africans in the public domain.Furthermore,most of these databases contain a relatively small number of subjects and labelled images.This paper proposes a large-scale African database named Chinese Academy of Sciences Institute of Automation(CASIA)-Iris-Africa that can be used as a complementary database for the iris recognition community to mediate the effect of racial biases on Africans.The database contains 28717 images of 1023 African subjects(2046 iris classes)with age,gender,and ethnicity attributes that can be useful in demographically sensitive studies of Africans.Sets of specific application protocols are incorporated with the database to ensure the database’s variability and scalability.Performance results of some open-source state-of-the-art(SOTA)algorithms on the database are presented,which will serve as baseline performances.The relatively poor performances of the baseline algorithms on the proposed database despite better performance on other databases prove that racial biases exist in these iris recognition algorithms.

关键词： African iris recognition racial bias iris image database biometrics iris recognition

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Application of CFD plug-ins integrated into urban and building design platforms for performance simulations:A literature review

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Frontiers of Architectural Research 2023年第1期12卷 148-174页

作者： Yongyu hu yunlong Peng Zhi Gao Fusuo Xu School of Architecture and Urban Planning Nanjing UniversityNanjing 210093China

The transformation of urban and building design into green development is conducive to alleviating resource and environmental problems.Building design largely determines pollutant emissions and energy consumption throughout the building life cycle.Full consideration of the impact of urban geometries on the microclimate will help construct livable and healthy cities.Computational fluid dynamics(CFD)simulations significantly improve the efficiency of assessing the microclimate and the performance of design schemes.The integration of CFD into design platforms by plug-ins marks a landmark development for the interaction of computer-aided design(CAD)and CFD,allowing architects to perform CFD simulations in their familiar design environments.This review provides a systematic overview of the classification and comprehensive comparison of CFD plug-ins in Autodesk Revit,Rhinoceros/Grasshopper,and Sketchup.The applications of CFD plug-ins in urban and building design are reviewed according to three types:single-objective,multi-objective,and coupling simulations.Two primary roles of CFD plug-ins integrated into the design process,including providing various micro-scale numerical simulations and optimizing the original design via feedback results,are analyzed.The issues of mesh generation,boundary conditions,turbulence models,and simulation accuracy during CFD plug-in applications are discussed.Finally,the limitations and future possibilities of CFD plug-ins are proposed.

关键词： Urban design Building design Computational fluid dynamics(CFD) Performance simulation Integration Optimization

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Construction of direct Z-scheme BPQDs-modified BiOBr thin film for enhanced photocatalytic performance under visible light irradiation

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Journal of Materiomics 2021年第5期7卷 1122-1130页

作者： Ziyu Yao huajun Sun Yunlong Hu Xiaofang Liu Yong Zhang State Key Laboratory of Silicate Materials for Architectures Center for Smart Materials and Device IntegrationSchool of Materials Science and EngineeringWuhan University of TechnologyWuhan430070China School of Chemistry Chemical Engineering and Life SciencesWuhan University of TechnologyWuhan430070China Advanced Ceramics Institute of Zibo New&High-Tech Industrial Development Zone Zibo255000China

Surface modification on photocatalytic thin films is long considered as an effective strategy to improve the degradation performance,which in turn helps to alleviate the worldwide environmental pollution issue.In this study,a direct Z-scheme photocatalytic system is constructed successfully by integrating black phosphorus quantum dots(BPQDs)on the surface of BiOBr thin film prepared by hydrothermal method.The optimal BPQDs/BiOBr-1 thin film presents remarkable enhanced photocatalytic activity for degrading methyl violet(MV)and tetracycline hydrochloride(TC),which is 3 and 3.65 times higher than that of pure BiOBr counterpart.The active species involved in the reaction are ^(+),·O_(2)^(-),and·OH,which determined by radical trapping experiments.The formation of direct Z-scheme photocatalytic system makes electrons assembled in the conduction band(CB)of BPQDs and holes gathered in the valence band(VB)of BiOBr,which supports the generation of h^(+) and·O_(2)^(-) and in turn accelerates the photocatalytic reaction.Besides,the improved efficiency of charge separation,enhanced visible light absorption and enlarged specific surface area also contributed to the enhanced photocatalytic performance of BPQDs/BiOBr.This work provides a feasible strategy for optimizing photocatalytic thin films via detailed analyzing the role of BPQDs in the construction of direct Z-scheme photocatalysts.

关键词： Photocatalytic thin films Direct Z-scheme Surface modification BPQDs BiOBr

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Enhanced Removal of Phenols by MIZ-Cu Nanozyme Exhibiting Laccase-like Activity and Broader Adaptability to Temperature and pH Conditions

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Chemical Research in Chinese Universities 2023年第6期39卷 1111-1118页

作者： WANG yunlong SUN Yue WANG Le ZHANG Hao hu Jiakang LI Yongxin Key Lab of Groundwater Resources and Environment of Ministry of Education Key Lab of Water Resources and Aquatic Environment of Jilin ProvinceCollege of New Energy and EnvironmentJilin UniversityChangchun 130021P.R.China

Phenolic compounds,classified as persistent organic pollutants,pose a significant threat to both human health and environmental safety.Therefore,the efficient removal of phenolic substances from water is of paramount importance.Laccase,a multicopper oxidase,is commonly utilized for the efficient removal of phenolic contaminants from water due to its highly effective catalytic activity towards phenolic compounds.However,natural laccase exhibits certain limitations that impede its practical implementation in industrial settings,including a restricted pH activity range,diminished enzymatic efficacy at elevated temperatures,and substantial cost implications.In this work,we prepared a nanozyme(MIZ-Cu,MIZ:2-methylimidazole)with laccase-like activity by coordinating 2-methylimidazole and copper.This nanozyme overcomes the deactivation issues observed in natural laccase under high temperature and alkaline conditions.The catalytic activity of the MIZ-Cu towards phenolic compounds surpasses that of natural laccase across a wide range of temperature and pH conditions.Under pH=9,80℃,and 500 mmol/L NaCl conditions,the removal rate of four phenols(catechol,hydroquinone,resorcinol,and phloroglucinol)by MIZ-Cu was much higher than that of natural laccase.The results also demonstrate exceptional removal rates in natural aquatic environments,thereby presenting a promising approach for the treatment of phenol-containing wastewater originating from industrial facilities.

关键词： Nanozyme Laccase Phenol Pollutant removal Wastewater treatment

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CMIP 6 models simulation of the connection between North/South Pacific Meridional Mode and ENSO

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Journal of Oceanology and Limnology 2024年第2期42卷 439-453页

作者： yunlong LU Junqiao FENG Dunxin hu Key Laboratory of Ocean Circulation and Waves Chinese Academy of SciencesQingdao 266071China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

The subtropical North and South Pacific Meridional Modes(NPMM and SPMM)are well known precursors of El Niño-Southern Oscillation(ENSO).However,relationship between them is not constant.In the early 1980,the relationship experienced an interdecadal transition.Changes in this connection can be attributed mainly to the phase change of the Pacific decadal oscillation(PDO).During the positive phase of PDO,a shallower thermocline in the central Pacific is responsible for the stronger trade wind charging(TWC)mechanism,which leads to a stronger equatorial subsurface temperature evolution.This dynamic process strengthens the connection between NPMM and ENSO.Associated with the negative phase of PDO,a shallower thermocline over southeastern Pacific allows an enhanced wind-evaporation-SST(WES)feedback,strengthening the connection between SPMM and ENSO.Using 35 Coupled Model Intercomparison Project Phase 6(CMIP6)models,we examined the NPMM/SPMM performance and its connection with ENSO in the historical runs.The great majority of CMIP6 models can reproduce the pattern of NPMM and SPMM well,but they reveal discrepant ENSO and NPMM/SPMM relationship.The intermodal uncertainty for the connection of NPMM-ENSO is due to different TWC mechanism.A stronger TWC mechanism will enhance NPMM forcing.For SPMM,few models can simulate a good relationship with ENSO.The intermodel spread in the relationship of SPMM and ENSO owing to SST bias in the southeastern Pacific,as WES feedback is stronger when the southeastern Pacific is warmer.

关键词： North and South Pacific Meridional Modes(NPMM and SPMM) El Niño-Southern Oscillation(ENSO) Pacific decadal oscillation(PDO) Coupled Model Intercomparison Project Phase 6(CMIP6)

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Effect of Cu content on microstructure and mechanical properties of in-situ β phases reinforced Ti/Zr-based bulk metallic glass matrix composite by selective laser melting(SLM)

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Journal of Materials Science & Technology 2021年第8期67卷 174-185页

作者： Xuehao Gao Xin Lin Qiaodan Yan Zihong Wang Xiaobin Yu Yinghui Zhou Yunlong Hu Weidong huang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design MUT ChinaNorthwestern Polytechnical UniversityXi'an710072China

In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu content on phase formation,microstructure,and mechanical properties is investigated.The average volume fraction and width of theβphase decreases with increasing Cu content,while a more amorphous phase and the(Ti,Zr)_(2)Cu phase forms.In the center zone of the molten pool,theβphase grows in the direction of the temperature gradient,and the amorphous phase distributes among theβphases.This occurs using:sphere morphology(for x=5),a more continuous elongated sphere and network morphology(for x=10),and network morphology(for x=15),respectively.In the edge zone of the molten pool,due to the smaller cooling rate and the existence of a partially molten zone,theβphase becomes coarser,and an amorphous phase forms for more continuous networks.Furthermore,the hardness improves significantly with increasing Cu content.No crack is found for x=5.Although the average volume fraction of theβphase for x=5 is about 90%,the compression yield strength is 1386±64 MPa,reaching to an average level of conventionally fabricated counterparts,due to finer microstructure,and twinning and martensitic transformation of theβphase.

关键词： Metallic glass Amorphous phase βPhase Bulk metallic glass matrix composites(BMGCs) Additive manufacturing(AM) Selective laser melting(SLM)

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Synthesis of Low-cost LiFePO_4 from Li_2CO_3 by a Novel Hydrothermal Method and Investigation on the Reaction Mechanism

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Journal of Wuhan University of Technology(Materials Science) 2015年第2期30卷 223-230页

作者：李向锋 hu yunlong LIU Fang 张昭 College of Chemical Engineering Sichuan University

Phspho-olivine Li Fe PO4 was synthesized from the relatively insoluble lithium source Li2CO3, proper iron and phosphorus sources（n（Li）：n（Fe）：n（P）=1：1：1） by a novel hydrothermal method. Afterwards, the optimal sample was mixed with glucose and two-step calcinated（500 ℃ and 750 ℃） under high-purity N2 to obtain the Li Fe PO4/C composite. The resultant samples were characterized by X-ray diffraction（XRD）, atomic absorption spectrometry（AAS）, scanning electron microscops（SEM）, transmission electron microscopy（TEM）, energy dispersive spectrometry（EDS）, elementary analysis（EA） and electrochemical tests. The results show that the optimal reaction condition is to set the reactant concentration at 0.5 mol·L^-1, the reaction temperature at 180 ℃ for 16 h duration. During the reaction course, an intermediate product NH4 Fe PO4·H2O was first synthesized, and then it reacted with Li＋ to form Li Fe PO4. The optimized Li Fe PO4 sample with an average particle size（300 to 500 nm） and regular morphology exhibits a relatively high discharge capacity of 84.95 m Ah· g^-1 at the first charge-discharge cycle（0.1C, 1C=170 m A·g^-1）. Moreover, the prepared Li Fe PO4/C composite shows a high discharge capacity of 154.3 m Ah·g^-1 at 0.1C and 128.2 m Ah·g^-1 even at 5C. Besides it has good reversibility and stability in CV test.

关键词： Li-ion battery LiFePO4 hydrothermal method Li2CO3 reaction mechanism

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One-step,in situ formation of WN-W_(2)C heterojunctions implanted on N doped carbon nanorods as efficient oxygen reduction catalyst for metal-air battery

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Nano Research 2023年第7期16卷 8773-8781页

作者： Yue Du Wenxue Chen Lina Zhou Rui hu Shizhu Wang Xueqing Li yunlong Xie Lun Yang Yisi Liu Zhenhui Liu Institute for Advanced Materials Hubei Normal UniversityHuangshi 435002China College of Material Science and Engineering Jiangsu Key Laboratory of Materials and Technology for Energy ConversionNanjing University of Aeronautics and AstronauticsNanjing 210016China

Transition metal nitrides and carbides have attracted intensive attentions in metal-air battery application due to their metallic electron transport behavior and high chemical stability toward the oxygen reduction reaction(ORR).Herein,the polyoxometalate@polyaniline composite derived WN-W_(2)C heterostructured composite(WN-W_(2)C@pDC)has been fabricated through an in situ nitriding-carbonization strategy,with WN-W_(2)C nanoparticles implanted on N doped carbon nanorods.Asfabricated WN-W_(2)C@pDC demonstrates prominent electrocatalytic performance towards ORR and excellent cycling stability in metal-air battery,which possesses positive half-wave potential and large diffusion limiting current density(0.81 V and 5.8 mA·cm^(-2)).Moreover,it demonstrates high peak power density of 157.4 mW·cm^(-2)as Al-air primary cathode and excellent stability at the discharge-charge test(>500 h)of Zn-air secondary battery.The excellent activity and durability of WNW_(2)C@pDC catalyst should be attributed to the combined effect of intimate WN-W_(2)C heterointerfaces,unique embedded nanoparticles structure,and excellent electrical media of N doped carbon,confirmed by a series of contrast experiments.

关键词： WN-W_(2)C heterojunctions polyoxometalate@polyaniline composite oxygen reduction reaction metal-air battery

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