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Building Simulation 2022年第9期15卷 1645-1660页

作者： Jianlin Ren junjie he Xiangfei Kong Hongwan Li School of Energy and Environmental Engineering Hebei University of TechnologyTianjin300401China Department of Environmental Engineering Sciences University of FloridaUSA

Walking-induced fluctuations have a significant influence on indoor airflow and pollutant *** study developed a method to quantify the robustness of ventilation systems in the control of walking-induced fluctuation *** were conducted in a full-scale chamber with four different kinds of ventilation systems:ceiling supply and side return(CS),ceiling supply and ceiling return(CC),side supply and ceiling return(SC),and side supply and side return(SS).The measured temperature,flow and pollutant field data was(1)denoised by FFT filtering or wavelet transform;(2)fitted by a Gaussian function;(3)feature-extracted for the range and time scale disturbance;and then(4)used to calculate the range scale and time scale robustness for different ventilation systems with dimensionless equations developed in this *** selection processes for FFT filtering and wavelet transform,FFT filter cut-off frequency,wavelet function,and decomposition layers are also discussed,as well as the threshold for wavelet denoising,which can be adjusted accordingly if the walking frequency or sampling frequency differs from that in other *** results show that for the flow and pollutant fields,the use of a ventilation system can increase the range scale robustness by 19.7%-39.4% and 10.0%-38.8%,respectively;and the SS system was 7.0%-25.7% more robust than the other three ventilation ***,all four kinds of ventilation systems had a very limited effect in controlling the time scale disturbance.

关键词： FFT filtering wavelet denoising Gaussian fitting feature extraction robust

Enhanced mechanical properties of Mg-3Al-1Zn alloy sheets through slope extrusion

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1343-1350页

作者： Huabao Yang Yanfu Chai Bin Jiang Chao he junjie he Qingshan Yang Ming Yuan School of Mechanical and Electrical Engineering Shaoxing UniversityShaoxing 312000China Tianjin Key Laboratory of Composite&Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China College of Materials Science and Engineering Yunnan UniversityKunming 650091China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

A novel extrusion approach,entitled slope extrusion(SE),was employed to manufacture AZ31(Mg-3Al-1 Zn,wt%)alloy *** microstructures,textures,and mechanical properties were investigated,compared with those of the AZ31 sheet fabricated by conventional extrusion(CE).Through the combination of finite element simulation and actual experiment,the ultimate results indicated that significant grain refinement(from 9.1 to 7.7 and 5.6μm)and strong basal texture(from 12.6 to 17.6 and 19.5 mrd)were achieved by the SE *** essence was associated with the additional introduced inclined interface in the process of SE,which could bring about more asymmetric deformation and stronger accumulated strain along the ND when compared with the process of *** a consequence,the SE sheets exhibited a higher yield strength(YS)and ultimate tensile strength(UTS)than the counterparts of the CE sheet,which was mainly assigned to the synergistic effects from grain refining and texture strengthening.

关键词： AZ31 Mg alloy sheets slope extrusion microstructure texture strength

Thermal Analysis of Glasses in TeO2-BaF2-LaF3 Systems

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Journal of Materials Science & Technology 2006年第3期22卷 411-413页

作者： Dongbing he junjie ZHANG Zhongchao DUAN Shixun DAI Lili HU Shanghai Institute of Optic and Fine Mechanics Chinese Academy of Sciences P.O. Box 800-211 Shanghai 201800China

Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides-MF2（M=Sr, Mg, Ca） on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.

关键词： Divalent metal fluorides Oxyfluoride tellurite glasses Thermal stability

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

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Acta Geochimica 2019年第2期38卷 202-215页

作者： Yan Zhang Runsheng Han Xing Ding junjie he Yurong Wang Geological Survey Center for Non-ferrous Mineral Resources Kunming University of Science and Technology State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Key Laboratory of Mineralogy and Metallogenic Guangzhou Institute of Geochemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

关键词： Metal precipitation Fluid mixing Sulfur species MVT lead-zinc ore deposits Carbonate-hosted lead-zinc deposits

Synthesis and electrochemical properties of Zn_3V_3O_8 as novel anode material

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Chinese Chemical Letters 2019年第3期30卷 806-808页

作者： Yunxia Jin junjie he Zaihua Ou Chuanqi Feng Guangxue Zhang Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Ministry of Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules Hubei University Nanxian Fanggu Middle School School of Nuclear Technology and Chemistry & Biology Hubei University of Science and Technology

Zn_3V_3O_8 two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The X-ray diffraction(XRD) and field emission scanning electron microscopy(SEM) are used to characterize the structure and morphology of the samples, and the battery testing system is used to investigate its electrochemical performance. The results show that the Zn_3V_3O_8 is successfully obtained using mix solvent(water:ethylene glycol =1:1), and the sample takes on morphology of two-dimensional sheets. The initial discharge capacity for Zn_3V_3O_8 two-dimensional micro sheets is 752.0 mAh/g at 100 mA/g in the voltage range of 0.01-3 V. After heat treatment in a tube furnace at 550 ℃, the sample had the initial discharge capacity as 1152.0 mAh/g and maintained it at 901.4 mAh/g after 100 cycles. The good electrochemical performance for Zn_3V_3O_8 two-dimensional micro sheets make it possible to be used as novel anode for lithium ion battery application.

关键词： Inorganic compound Inorganic synthesis Electronic materials Anode material Zn3V3O8

Molding of polyether ether ketone(PEEK)and its composites:a review

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第10期25卷 788-823页

作者： Zhengchuan GUO junjie he Ruoxiang GAO Yifeng PAN Chengqian ZHANG Jianzhong FU Peng ZHAO The State Key Laboratory of Fluid Power and Mechatronic Systems College of Mechanical EngineeringZhejiang UniversityHangzhou 310058China The Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province College of Mechanical EngineeringZhejiang UniversityHangzhou 310058China Center for X-Mechanics Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China

Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and *** and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal ***,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic *** this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D *** also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its ***,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural ***,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.

关键词： Polyether ether ketone(PEEK) Composites Extrusion molding Hot compression molding Injection molding 3D printing

Relating Initial Texture to Deformation Behavior During Cold Rolling and Static Recrystallization Upon Subsequent Annealing of an Extruded WE43 Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1793-1811页

作者： Qinghang Wang Haowei Zhai Hongbo Xia Lintao Liu junjie he Dabiao Xia Hong Yang Bin Jiang School of Mechanical Engineering Yangzhou UniversityYangzhou 225127China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China School of Materials and Energy Yunnan UniversityKunming 650599China The Center of New Energy Materials and Manufacturing Jihua LaboratoryFoshan 528000China

Deformation behaviors during cold rolling and static recrystallization behaviors upon subsequent annealing of an extruded WE43 alloys with different initial textures were investigated in this *** types of differently textured WE43 initial alloys were labeled as samplesⅠ,ⅡandⅢ.The results showed that multiple twinning modes and basal slip dominated the deformation of samples during cold ***-rolled sampleⅠactivated the larger number of double twins with high strain energy,accompanied by the more uniform strain distribution,than cold-rolled samplesⅡandⅢ.During subsequent annealing,recrystallized grains preferentially occurred in double twins,twin-twin intersections and grain boundaries,thereby making cold-rolled sampleⅠhave the more rapid recrystallization *** recrystallization textures formed in three types of cold-rolled samples at the recrystallization nucleation stage,and they never largely changed with the annealing time due to the uniform grain growth induced by the solute drag and the precipitation pinning at grain *** full recrystallization,the grain growth was controlled by the solute drag,instead of precipitates which were re-dissolved into the ***,the nucleation and growth kinetics of static recrystallization were calculated,and the effects of initial texture on activation energies of recrystallization nucleation and growth were discussed.

关键词： WE43 alloy Texture Cold rolling Annealing Static recrystallization

Orbitally driven giant thermal conductance associated with abnormal strain dependence in hydrogenated graphene-like borophene

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npj Computational Materials 2019年第1期5卷 752-759页

作者： Jia he Dengfeng Li Yan Ying Chunbao Feng junjie he Chengyong Zhong Hangbo Zhou Ping Zhou Gang Zhang School of Science Chongqing University of Posts and TelecommunicationsChongqing 400065China Institute of High Performance Computing A*STARSingapore 138632Singapore

heat energy in solids is carried by phonons and ***,in most two-dimensional(2D)materials,the contribution from electrons to total thermal conduction is much lower than that for *** this work,through first-principles calculations combined with non-equilibrium Green’s function theory,we studied electron and phonon thermal conductance in recently synthesized 2D hydrogen *** hexagonal boron network with bridging hydrogen atoms is suggested to exhibit comparable lattice thermal conductance(4.07 nWK−1 nm−2)as graphene(4.1 nWK−1 nm−2),and similar electron thermal conductance(3.6 nWK−1 nm−2),which is almost ten times that of *** a result,total thermal conductance of 2D hydrogen boride is about two-fold of graphene,being the highest value in all known 2D ***,tensile strain along the armchair direction leads to an increase in carrier density,significantly increasing electron thermal *** increase in electron thermal conductance offsets the reduction in phonon thermal conductance,contributing to an abnormal increase in thermal *** demonstrate that the high electron density governs extraordinarily high thermal conductance in 2D hydrogen boride,distinctive among 2D materials.

关键词： strain thermal Orbital

Hot-deformation kinetics analysis and extrusion parameter optimization of a dilute rare-earth free magnesium alloy

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Journal of Magnesium and Alloys 2023年第9期11卷 3302-3322页

作者： Qinghang Wang Haowei Zhai Zhaoyang Jin junjie he Qin Yang Wenjun Liu Yulong Li Daolun Chen School of Mechanical Engineering Yangzhou UniversityNo.196 West Huayang RoadHangjiangYangzhou225127China School of Materials and Energy Yunnan UniversityKunming650599China Changan Auto Global R&D Center Chongqing401120China College of Materials Science and Engineering Chongqing University of TechnologyChongqing400054China Department of Mechanical and Industrial Engineering Toronto Metropolitan University(formerly Ryerson University)TorontoON M5B 2K3Canada

The fundamental research on thermo-mechanical conditions provides an experimental basis for high-performance Mg-Al-Ca-Mn ***, there is a lack of systematical investigation for this series alloys on the hot-deformation kinetics and extrusion parameter optimization. here, the flow behavior, constitutive model, dynamic recrystallization(DRX) kinetic model and processing map of a dilute rare-earth free Mg-1.3Al-0.4Ca-0.4Mn(AXM100, wt.%) alloy were studied under different hot-compressive conditions. In addition, the extrusion parameter optimization of this alloy was performed based on the hot-processing map. The results showed that the conventional Arrhenius-type strain-related constitutive model only worked well for the flow curves at high temperatures and low strain rates. In comparison, using the machine learning assisted model(support vector regression, SVR) could effectively improve the accuracy between the predicted and experimental values. The DRX kinetic model was established, and a typical necklace-shaped structure preferentially occurred at the original grain boundaries and the second phases. The DRX nucleation weakened the texture intensity, and the further growth caused the more scattered basal texture. The hot-processing maps at different strains were also measured and the optimal hot-processing range could be confirmed at the deformation temperatures of 600~723 K and the strain rates of 0.018~0.563 s^(-1). Based on the optimum hot-processing range, a suitable extrusion parameter was considered as 603 K and 0.1 mm/s and the as-extruded alloy in this parameter exhibited a good strength-ductility synergy(yield strength of ~ 232.1 MPa, ultimate strength of ~ 278.2 MPa and elongation-to-failure of ~ 20.1%). Finally, the strengthening-plasticizing mechanisms and the relationships between the DRXed grain size, yield strength and extrusion parameters were analyzed.

关键词： Mg-Al-Ca-Mn alloy Constitutive model Dynamic recrystallization kinetic model Extrusion parameter optimization Strengthening-plasticizing mechanisms

Ameliorating mechanical properties and reducing anisotropy of as-extruded Mg-1.0Sn-0.5Ca alloy via Al addition

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Progress in Natural Science:Materials International 2021年第5期31卷 722-730页

作者： Yanfu Chai Lei Shan Bin Jiang Huabao Yang Chao he Wenxing Hao junjie he Qingshan Yang Ming Yuan Fusheng Pan School of Mechanical and Electrical Engineering Shaoxing University State Key Laboratory of Mechanical Transmissions College of Materials Science and Engineering Chongqing University College of Materials Science and Engineering Yunnan University School of Metallurgy and Material Engineering Chongqing University of Science and Technology

Effects of Al addition to a Mg–Sn–Ca ternary alloy on its microstructure and tensile properties after extrusion were studied via extrusion of Mg-1.0 Sn-0.5 Ca-x Al(x = 0, 0.8, 2.4 wt%) sheets and analysis of the extruded *** results showed that Al addition not only refined the grain size(from 9.8 ± 0.7 μm to 8.3 ± 0.4 μm and7.6 ± 0.5 μm) but also accelerated the generation of more second phase(from 0.98 to 1.72 and 4.32%). Except for the CaMgSn and Mg2Ca in Mg-1.0Sn-0.5 Ca alloy, new phase(Mg, Al)2Ca appeared after Al addition. The addition of Al into Mg–Sn–Ca alloy induced the textural variation from an initially ED-split double-peaked texture to a weakened texture, i.e., divergent elliptical texture, due to the effect of particle stimulated nucleation. This eventually contributed to the improvement of mechanical anisotropy as well as the higher Hc value and *** the strain hardening behavior when tension along the TD, the prolonged stage II of Al-modified alloys was closely connected with the additional TD textural components, accelerating the activation of more basal slip. The decreased θIII0 in stage III of Al-modified alloys is beneficial to the grain refinement and the emergence of more second phase.

关键词： Mg–Sn–Ca alloy Al content Microstructure Texture Mechanical anisotropy