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Investigation into the stress-strain compatibility and fracture behaviour of a TC18 titanium alloy with a multistage lamellar microstructure

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Progress in Natural Science:Materials International 2024年第5期34卷 1039-1048页

作者： Zhongxiang Li Zhaoxin Du jun cheng Zhiyong Yue Tianhao Gong Xudong Kang Yongcheng Zhu School of Materials Science and Engineering Inner Mongolia University of Technology Collaborative Innovation Center of Non-ferrous Metal Materials and Processing Technology Co-constructed By the Province and Ministry Inner Mongolia Autonomous Region Inner Mongolia University of Technology Northwest Institute for Nonferrous Metal Research Shanxi Key Laboratory of Biomedical Metal Materials School of Mechanical Engineering Inner Mongolia University of Technology

Understanding the fracture mechanism is essential for optimizing the mechanical properties of titanium *** relationship between fracture behaviour and the multistage lamellar microstructure of the TC18(Ti–5Al–5Mo–5V–1Cr–1Fe) alloy was investigated via in situ tensile and three-point bending tests. The results indicate that the TC18 alloy, featuring a multistage lamellar microstructure(including a β matrix, primary lamellar α phase, bundles, and secondary lamellar α phase), exhibits an excellent combination of strength and ductility. The precipitation of the secondary lamellar α phase significantly enhances the alloy's strength but weakens the stress-strain compatibility of the microstructure. This results in a smaller crack-tip plastic zone(CTPZ) and causes dislocations to concentrate more at the grain boundaries and, to a lesser extent, at the phase interfaces. Consequently, in the later stages of crack propagation, microvoids and microcracks tend to form at dislocation pile-ups. With increasing stress, these microvoids and microcracks rapidly coalesce, leading to a greater proportion of intergranular fracture and thus reducing the fracture toughness of the alloy.

关键词： TC18titanium alloys In situ stretching Crack-tip plastic zone (CTPZ) Stress‒strain compatibility Fracture behaviour

New role of α phase in the fracture behavior and fracture toughness of a β-type bio-titanium alloy

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1756-1763页

作者： Ran Wang Xiu Song Lei Wang Yang Liu Mitsuo Niinomi Deliang Zhang jun cheng Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Institute for Materials Research Tohoku University2-1-1 KatahiraAoba-kuSendai 980-8577Japan Meijo University 1-501 ShiogamaguchiTempaku-kuNagoya 468-8502Japan Nagoya University Furo-choChikusa-kuNagoya 464-8601Japan Shaanxi Key Laboratory of Biomedical Metal Materials Northwest Institute for Nonferrous Metal ResearchXi’an 710016China

The role of α precipitates formed during aging in the fracture toughness and fracture behavior of β-type bio-titanium alloy Ti–29Nb–13Ta–4.6Zr(TNTZ) was studied. Results showed that the fracture toughness of the TNTZ alloy aged at 723 K decreases to the minimum of 72.07–73.19 kJ·m^(-2)when the aging time is extended to 4–8 h and then gradually increases and reaches 144.89 kJ·m^(-2)after 72 h. The decrease in fracture toughness within the aging time of 4–8 h is caused by the large stress concentration at the tip of acicular α precipitates with a high aspect ratio and the preferential crack propagation along the inhomogeneous acicular α precipitates distributed in “V-shape” and “nearly perpendicular shape”. When the aging time is extended to 8–72 h, the precrack tip is uniformly blunted, and the crack is effectively deflected by α precipitates with multi long axis directions, more high homogeneity, low aspect ratio, and large number density. Analysis of the effect of αprecipitates on the fracture behavior suggested that the number of long axis directions of α precipitates is the key controlling factor for the fracture behavior and fracture toughness of the TNTZ alloy aged for different times.

关键词： fracture toughness Ti-29Nb-13Ta-4.6Zr alloy agedαphase crack tip blunting

Tuberculosis Infection Control Project Management Experience and Its Application in COVID-19 Response

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China CDC weekly 2020年第34期2卷 666-668页

作者： Qingyun Sun Xiaofeng Yan cheng Chen Xuemei Jiang jun cheng Department of Nosocomial Infection Control and Prevention Chong Qing Public Health Medical CenterChong QingChina National Center for Tuberculosis Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina

The outbreak of COVID-19 resulted in many infections,including patients in health care settings(1).Although the main mode of transmission of COVID-19 is by droplets,both tuberculosis(TB)and COVID-19 are respiratory infections that can be spread by airborne ***,a set of systematic and comprehensive nosocomial infection control policies is necessary to control infectious sources,block transmission,and protect people at risk in health care settings.

关键词： respiratory tuberculosis infection

Robust leaderless time-varying formation control for unmanned aerial vehicle swarm system with Lipschitz nonlinear dynamics and directed switching topologies

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Chinese Journal of Aeronautics 2022年第1期35卷 124-136页

作者： Yuhang KANG Yu KUANG jun cheng Bangchu ZHANG Yahui QI Shaolei ZHOU Kai MAO Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China School of Basic Science Naval Aviation UniversityYantai 264001China School of Aeronautics and Astronautics Sun Yat-Sen UniversityGuangzhou 510275China

This paper tackles the robust leaderless Time-Varying Formation(TVF)control problem for the Unmanned Aerial Vehicle(UAV)swarm system with Lipschitz nonlinear dynamics,external disturbances and directed switching *** comparison with the previous achievements on formation control problems,the UAV swarm system with Lipschitz nonlinear dynamics can accomplish the pre-designed TVF while tracking a pre-given trajectory which is produced by a virtual leader UAV in the presence of external ***,by applying the consensus theory,a TVF controller is developed with the local neighborhood status information,the errors of real time status of all UAVs,the expected formation configuration and the pre-given trajectory under directed switching ***,through a certain matrix variable substitution,the UAV swarm system formation control issue is transformed into a lower dimensional asymptotically stable control ***,by introducing the minimum dwell time,the design steps of formation control algorithm are further *** the meantime,the stability of the UAV swarm system is analyzed through the construction of a piecewise continuous Lyapunov functional and via the Linear Matrix Inequalities(LMIs)***,the comparison results of a numerical simulation are elaborated to verify the validity of the proposed approach.

关键词： Directed switching topologies Lipschitz nonlinear dynamics Lyapunov functional Swarm system Time-Varying Formation(TVF) Unmanned Aerial Vehicle(UAV)

Gravitational wave echoes from strange quark stars in the equation of state with density-dependent quark masses

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Nuclear Science and Techniques 2023年第11期34卷 112-119页

作者： Jian‑Feng Xu Lei Cui Zhen‑Yan Lu cheng‑jun Xia Guang‑Xiong Peng School of arts and sciences Suqian UniversitySuqian 223800China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

According to the recent studies,the gravitational wave(GW)echoes are expected to be generated by quark stars composed of ultrastiff quark *** ultrastiff equations of state(EOS)for quark matter were usually obtained either by a simple bag model with artificially assigned sound velocity or by employing interacting strange quark matter(SQM)depicted by simple reparameterization and *** this study,we investigate GW echoes with EOSs for SQM in the framework of the equivparticle model with density-dependent quark masses and pairing *** conclude that strange quark stars(SQSs)can be sufficiently compact to possess a photon sphere capable of generating GW echoes with frequencies in the range of approximately 20 ***,SQSs cannot account for the observed 72 Hz signal in GW170817 ***,we determined that quark-pairing effects play a crucial role in enabling SQSs to satisfy the necessary conditions for producing these types of echoes.

关键词： Strange quark star Gravitational wave echoes Color-flavour-locked phase Strange quark matter

Boosting fast interfacial Li^(+)transport in solid-state Li metal batteries via ultrathin Al buffer layer

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Nano Research 2023年第5期16卷 6825-6832页

作者： Shengnan Zhang Qing Sun Guangmei Hou jun cheng Linna Dai Jianwei Li Lijie Ci Key Laboratory for Liquid-Solid Structural Evolution&Processing of Materials(Ministry of Education) Research Center for Carbon NanomaterialsSchool of Materials Science and EngineeringShandong UniversityJinan 250061China School of Light Industry and Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China State Key Lab of Advanced Welding and Joining School of Materials Science and EngineeringHarbin Institute of Technology(Shenzhen)Shenzhen 518055China School of Science Hubei University of TechnologyWuhan 430068China University of Health and Rehabilitation Sciences Qingdao266071China

Na superionic conductor(NASICON)-type Li_(1.5)Al_(0.5)Ge_(0.5)P_(3)O_(12)(LAGP)solid state electrolytes(SSEs)have attracted significant interests thanks to the prominent ionic conductivity(>10^(–4)S·cm^(–1))at room temperature and superb stability in ***,its application has been hindered by the lithium dendrites and the intrinsic interfacial instability of LAGP towards metallic Li,***,by magnetron sputtering(MS),an ultrathin Al film is deposited on the surface of the LAGP pellet(Al-LAGP).By in-situ alloying reaction,the spontaneously formed LiAl buffer layer inhibits the side reaction between LAGP SSEs and Li metal,induces the uniform distribution of interfacial electric field as *** functional theory(DFT)calculations demonstrate that the LiAl alloy surface promotes the diffusion of lithium atoms due to the lower energy barrier,thereby inhibiting the formation of lithium ***,the Li/Al-LAGP-Al/Li symmetric cells show a low resistance of 210Ωand a durable lifespan over 1,200 h at a high current density of 0.1 mA·cm^(-2).Assembled all solid state lithium metal batteries(ASSLMBs)with LiFePO_(4)(LFP)cathode significantly improve cycle stability and rate performance,proving a promising stabilization strategy towards the NASIOCN type electrolyte/anode interface in solid state Li metal batteries.

关键词： Li_(1.5)Al_(0.5)Ge_(0.5)P_(3)O_(12) solid-state battery Li+transport interfacial modification Al buffer

Characterization of wet microalgal cells pretreated with steam for lipid extraction

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Chinese Journal of Chemical Engineering 2021年第9期34卷 114-120页

作者： Wenlu Song Rui Huang Hao Guo Chunguang Yin Chuanling Wang jun cheng Weijuan Yang Department of Life Science and Engineering Jining UniversityJining 273155China The Electrical Engineering College Guizhou UniversityGuiyang 550025China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027China ShanDong Fanpu Analytic Co. LtdJining 272000China

Steam pretreatment was employed to disrupt Microalgal cells for lipids *** of steam pretreatment on microstructure of microalgal cells were investigated through scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Effect of treatment on lipid extraction was also *** cell walls were distorted after steam pretreatment due to the hydrolysis of organic macromolecules contained in cell *** curvature was increased from 1.88×10^(-6) m^(-1) to 1.43×10^(-7) m^(-1) after treatment with the steam at 130℃.The fractal dimension of microalgal cells increased from 1.25 to 1.30 after pretreatment for 15 min,and further increased to 1.47 when the pretreatment time was increased to 60 *** steam pretreatment temperature and time enhanced the hydrolysis of organic macromolecules,and finally destroyed microalgal cell walls at pretreatment temperature of 130℃and pretreatment time of 60 *** extracted from wet microalgal was significantly increased(2.1-fold)after pretreatment.

关键词： Chlorella pyrenoidosa Steam pretreatment Cell wall disruption Lipids extraction

Modified ulcer debridement in the treatment of the superficial fungal infection of the cornea

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International Journal of Ophthalmology(English edition) 2018年第2期11卷 223-229页

作者： jun-Yi Wang Dian-Qiang Wang Xiao-Lin Qi jun cheng Li-Xin Xie Department of Comea Qingdao Eye HospitalShandong Eye InstituteShandong Academy of Medical SciencesQingdao 266071Shandong ProvinceChina

AIM： To evaluate the efficacy of modified corneal ulcer debridement in superficial fungal keratitis unresponsive to ***： A total of 209 patients（209 eyes） with fungal keratitis, involving no more than 50% of the stromal depth and not responding to antifungal agents for 2 wk, were recruited in this retrospective, noncomparative study. The patients were treated with modified corneal ulcer debridement. All visible corneal infiltrates were removed under an operating microscope to obtain a clean stromal bed and smooth incised edges. Antifungal drugs were used immediately after surgery. Healing time of the ulcers was recorded. Fungal recurrence, visual acuity, corneal thickness and risk factors for treatment failure were ***： The follow-up was 13.6±5.8m o. The corneal ulcers healed in 195 of 209 eyes（93.3%）, with a mean healing time of 8.4±6.8 d. The other 14 eyes were further treated by penetrating keratoplasty（PK）（1 eye）, anterior lamellar keratoplasty（LK）（7 eyes）, conjunctival flap covering（4 eyes） or amniotic membrane transplantation（2 eyes）. The best corrected visual acuity（BCVA） was ≥20/70 in 80.3% of the eyes, ≥20/40 in 56.9% of the eyes, and ≥20/25 in 27.3% of the eyes. The corneas at the lesions became thinner, but all in the safe range. No fungal recurrence or corneal ectasis developed during the follow-up. The risk of treatment failure was higher in patients with preoperative hypopyon（P=0.036） and ever using steroid（P=0.025）.CONCLUSION： Modified surgical debridement is a simple and effective method for the treatment of superficial fungal infection of the cornea, with improved visual acuity and no recurrence. Such an intervention in time can rapidly control fungal infection and largely shorten corneal ulcer healing time.

关键词： fungal keratitis superficial fungal infection debridement cornea ulcer corneal scraping

QUALITATIVE ANALYSIS OF DYNAMICAL BEHAVIOR FOR AN IMPERFECT INCOMPRESSIBLE NEO-HOOKEAN SPHERICAL SHELL

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Applied Mathematics and Mechanics(English Edition) 2005年第8期26卷 973-981页

作者： YUAN Xue-gang（袁学刚） ZHUZheng-you（朱正佑） cheng Chang-jun（程昌钧） Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 P. R. China Department of Mathematics and Information Science Yantai University Yantai 264005 Shandong Province P. R. China

The radial symmetric motion problem was examined for a spherical shell composed of a class of imperfect incompressible hyper-elastic materials, in which the materials may be viewed as the homogeneous incompressible isotropic neo-Hookean material with radial perturbations. A second-order nonlinear ordinary differential equation that describes the radial motion of the inner surface of the shell was obtained. And the first integral of the equation was then carded out. Via analyzing the dynamical properties of the solution of the differential equation, the effects of the prescribed imperfection parameter of the material and the ratio of the inner and the outer radii of the underformed shell on the motion of the inner surface of the shell were discussed, and the corresponding numerical examples were carded out simultaneously. In particular, for some given parameters, it was proved that, there exists a positive critical value, and the motion of the inner surface with respect to time will present a nonlinear periodic oscillation as the difference between the inner and the outer presses does not exceed the critical value. However, as the difference exceeds the critical value, the motion of the inner surface with respect to time will increase infinitely. That is to say, the shell will be destroyed ultimately.

关键词： imperfect incompressible neo-Hookean material dynamical behavior critical value nonlinear periodic oscillation