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Suppression of grazing-induced instability in single degree-of-freedom impact oscillators

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Applied Mathematics and Mechanics(English Edition) 2019年第1期40卷 97-110页

作者： shan yin Guilin WEN Xin WU School of Mechanical and Electric Engineering Guangzhou University State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan University School of Mechanical Engineering Hunan Institute of Engineering

As a typical non-smooth bifurcation, grazing bifurcation can induce instability of elementary near-grazing impact periodic motion in impact oscillators. In this paper,the stability for near-grazing period-one impact motion to suppress grazing-induced instabilities is analyzed, based on which, a control strategy is proposed. The commonly-used leading order zero time discontinuity mapping is extended to a higher order one to aid the perturbation analysis of the characteristic equation. It is shown that the degenerate grazing bifurcation can eliminate the singular term in the characteristic equation, leading to bounded eigenvalues. Based on such a precondition, the bounded eigenvalues are further restricted inside the unit circle, and a continuous transition between non-impact and controlled impact motion is observed. One discrete feedback controller that changes the velocity of the oscillator based on the selected Poincar′e sections is adopted to demonstrate the control procedure.

关键词： grazing-induced instability higher order discontinuity mapping eigenvalue perturbation degenerate grazing bifurcation

Microstructural stability of 9-12%Cr ferrite/martensite heat-resistant steels

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Frontiers of Materials Science 2013年第1期7卷 1-27页

作者： Wei YAN Wei WANG Yi-yin shan Ke YANG Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The microstructural evolutions of advanced 9–12%Cr ferrite/martensite heat-resistant steels used for power generation plants are reviewed in this article. Despite of the small differences in chemical compositions, the steels share the same microstructure of the as-tempered martensite. It is the thermal stability of the initial microstructure that matters the creep behavior of these heat-resistant steels. The microstructural evolutions involved in 9–12%Cr ferrite heat-resistant steels are elaborated, including (1) martensitic lath widening, (2) disappearance of prior austenite grain boundary, (3) emergence of subgrains, (4) coarsening of precipitates, and (5) formation of new precipitates, such as Laves-phase and Z-phase. The former three microstructural evolutions could be retarded by properly disposing the latter two. Namely improving the stability of precipitates and optimizing their size distribution can effectively exert the beneficial influence of precipitates on microstructures. In this sense, the microstructural stability of the tempered martensite is in fact the stability of precipitates during the creep. Many attempts have been carried out to improve the microstructural stability of 9–12%Cr steels and several promising heat-resistant steels have been developed.

关键词： heat-resistant steel microstructure martensite precipitate microstructural evolution

Structures and magnetic relaxation properties of cyclopentadienyl/β-diketonate/trispyrazolylborate hybridized dysprosium single-molecule magnets

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Chinese Chemical Letters 2023年第8期34卷 467-471页

作者： Lu Zhang Jin Xiong yin-shan Meng Tao Liu State Key Laboratory of Fine Chemicals Dalian University of TechnologyDalian 116024China Department of Chemistry Carnegie Mellon UniversityPittsburghPA 15213United States

The combination of cyclopentadiene,β-diketonate and tripyrazoylborate ligands with dysprosium ion afforded five mononuclear compounds:[(Cp)2Dy(Tp∗)](1Dy),[(Cp)Dy(Tp∗)Cl(THF)](2Dy),[(Cp)Dy(Tp)Cl(THF)](3Dy),[(DBM)Dy(Tp)Cl(THF)](4Dy),[{(Tp)Dy(DBM)_(2)(H_(2)O)}·THF](5Dy)(Cp=cyclopentadiene;Tp∗=hydrotris(3,5-dimethyl-1-pyrazolyl)borate;Tp=hydrotris(1-pyrazolyl)borate;DBM=dibenzoylmethanoate).Magnetic study revealed that 1Dy and 3Dy exhibited typical butterfly-type *** susceptibility study combined with ab initio calculations indicated that the magnetic relaxation behaviors of 1Dy–4Dy were governed by the Orbach and Raman processes under applied DC ***,3Dy showed two-step magnetic relaxation,which was attributed to the static disordering of the coordinated THF *** anisotropy analysis indicated that it was the relative strength of the interactions between DyIII and surrounding ligands that determined the orientation of the magnetic easy axis.

关键词： Single-molecule magnets Lanthanide complexes Magnetic anisotropy Magnetic relaxations Quantum tunneling of magnetization

A novel laminated metal composite with superior interfacial bonding composed of ultrahigh strength maraging steel and 316L stainless steel

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Journal of Iron and Steel Research International 2020年第4期27卷 433-439页

作者： Le Zhang Wei Wang M.Babar Shahzad Yi-yin shan Ke Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016LiaoningChina School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026AnhuiChina Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina

A 5-layer laminated metal composite composed of ultrahigh-strength maraging steel and ductile 316L stainless steel was fabricated by hot pressing in vacuum and post-heat *** characterization on hierarchical structure of the composite before and after heat treatment was made by optical microscopy,scanning electron microscopy and electron back-scattered diffraction technique,***,the difference of mechanical performance on both sides of the interface was characterized by nano-hardness *** tensile test showed that superior interfacial bonding was achieved due to the micro-‘bite’structure between the two steels without obvious defects or oxides at the interface and with coordinated deformation of the two ***,a laminated metal composite consisting of two different constituents with extreme difference in strength can be well fabricated.

关键词： Maraging steel Austenitic stainless steel Laminated metal composite Hierarchical structure Interfacial

Torsional deformation-induced gradient hierarchical structure in a 304 stainless steel

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Journal of Iron and Steel Research International 2021年第6期28卷 722-728页

作者： Jia-long Tian Guang Hu Wei Wang Yi-yin shan Zhou-hua Jiang School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina Institute of Metal Research Chinese Academy of SciencesShenyang 110016LiaoningChina Shenyang RongRong Science and Technology Co. Ltd.Shenyang 110000LiaoningChina State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

After applying torsion to cylindrical 304 stainless steel samples,a gradient structure along the radial direction was *** was found that the volume fraction of a0-martensite increased gradually from the center to the surface of *** possibility of deformation-induced martensitic transformation was analyzed theoretically,whose conclusions were consistent with the experimental *** was found that torsional deformation could produce abundant deformation twin and deformation-induced martensite,which could affect the tensile property of steel *** existence of deformation and martensite during torsion could increase the strength but deteriorate the ductility dramatically during the tensile test,which should be attributed to the weakening of work hardening *** a result of severe deformation,both strain-induced and stress-induced martensite have been ***,two types of martensitic transformation mechanisms during torsional deformation were discussed.

关键词： Gradient material Torsional deformation Thermodynamic calculation 304 stainless steel Martensitic transformation

Failure evolution and disaster prediction of rock under uniaxial compression based on non-extensive statistical analysis of electric potential

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International Journal of Mining Science and Technology 2024年第7期34卷 975-993页

作者： Tiancheng shan Zhonghui Li Haishan Jia Enyuan Wang Xiaoran Wang Yue Niu Xin Zhang Dong Chen shan yin Quancong Zhang State Key Laboratory of Coal Mine Disaster Prevention and Control China University of Mining and TechnologyXuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

Rock failure can cause serious geological disasters,and the non-extensive statistical features of electric potential(EP)are expected to provide valuable information for disaster *** this paper,the uniaxial compression experiments with EP monitoring were carried out on fine sandstone,marble and granite samples under four displacement *** Tsallis entropy q value of EPs is used to analyze the selforganization evolution of rock *** the influence of displacement rate and rock type on q value are explored by mineral structure and fracture modes.A self-organized critical prediction method with q value is *** results show that the probability density function(PDF)of EPs follows the q-Gaussian *** displacement rate is positively correlated with q *** the displacement rate increasing,the fracture mode changes,the damage degree intensifies,and the microcrack network becomes *** influence of rock type on q value is related to the burst intensity of energy release and the crack fracture *** q value of EPs can be used as an effective prediction index for rock failure like b value of acoustic emission(AE).The results provide useful reference and method for the monitoring and early warning of geological disasters.

关键词： Electric potential Non-extensive statistical feature Displacement rate q-Gaussian distribution Precursor prediction Rock materials

Hot Deformation Behavior of an Ultra-High-Strength Fe–Ni–Co-Based Maraging Steel

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Acta Metallurgica Sinica(English Letters) 2019年第9期32卷 1161-1172页

作者： Le Zhang Wei Wang M. Babar Shahzad Yi-yin shan Ke Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Hot processing behavior of an ultra-high-strength Fe–Ni–Co-based maraging steel was studied in temperature range of 900–1200℃and strain rate range of 0.001–10 s^-*** processing parameters and optimum hot working window were characterized via flow stress analysis,constitutive equation construction,hot processing map calculation and microstructure evolution,*** strain value for dynamic recrystallization was determined through theoretical mathematical differential method:the inflection point ofθ–σand-αθ/ασ-σ*** was found that the flow stress increased with the decrease in deformation temperature and increase in the strain *** power dissipation maps in the strain range of 0.1–0.6 were entirely similar with the tendency of contour lines which implied that strain had no strong effect on the dissipation ***,the instability maps showed obvious strain sensitivity with increasing strain,which was ascribed to the flow localization and *** optimized hot processing window of the experimental steel was obtained as 1100–1200℃/0.001–1 s^-1 and 1000–1100℃/0.001–0.1 s^-1,with the efficiency range of 20–40%.Owing to high Mo content in the experimental steel,high dynamic activation energy,Q=439.311 kJ mol^-1,was achieved,indicating that dynamic recrystallization was difficult to occur in the hot deformation process,which was proved via microstructure analysis under different hot deformation conditions.

关键词： Maraging steel Hot working Dynamic recrystallization Constitutive equation Hot processing map

Approaching the uniaxiality of magnetic anisotropy in singlemolecule magnets

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Science China Chemistry 2023年第3期66卷 683-702页

作者： Chen Wang yin-shan Meng shang-Da Jiang Bing-Wu Wang Song Gao School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070China Beijing National Laboratory of Molecular Science Beijing Key Laboratory for Magnetoeletric Materials and DevicesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Fine Chemicals Dalian University of TechnologyDalian 116024China Spin-X Institute School of Chemistry and Chemical EngineeringState Key Laboratory of Luminescent Materials and DevicesGuangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional MaterialsSouth China University of TechnologyGuangzhou 510641China

Single-molecule magnets(SMMs),which can exhibit slow magnetization relaxation and bulk-magnet-like hysteresis of purely molecular origin,are promising candidates for high-density information storage,molecular spintronics,and quantum *** realize their applications,it is crucial to improve the blocking temperature(TB)and the effective relaxation barrier(Ueff).Three decades of multidisciplinary research have yielded distinct SMMs with a state-of-the-art Ueff of up to 2,000 K and a TB of up to the liquid nitrogen *** strategies have been investigated and summarized,which revealed that enhancing the uniaxiality of magnetic anisotropy is critical for constructing high-performance ***,magnetic anisotropy,a key property that connects the molecular structure symmetry and performance of SMMs,plays a fundamental role in dictating magneto-structural *** and employing magnetic anisotropy would be significantly beneficial for rationally designing high-performance *** review focuses on the magnetic anisotropy of *** illustrate the origin and manifestation of magnetic anisotropy in mononuclear 3d-and 4f-block metal *** then introduce developed approaches to investigate magnetic anisotropy both theoretically and *** SMMs by optimizing uniaxial magnetic anisotropy through lanthanide metallocene,symmetry controlling,and low-coordination approaches are ***,the remaining challenges and opportunities in this field will be discussed.

关键词： single-molecule magnets magnetic anisotropy uniaxiality lanthanide

Dawazisaurus Brevis, A New Eosauropterygian From the Middle Triassic of Yunnan, China

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Acta Geologica Sinica(English Edition) 2016年第2期90卷 401-424页

作者： CHENG Yen-nien WU Xiao-chun TAMAKI SATO shan His-yin National Museum of Natural Science 1 Kuan Chien Road Taichung Taiwan 40453 China Department of Earth Sciences National Cheng Kung University 1 University Road Tainan Taiwan 701 China Canadian Museum of Nature PO Box 3443 STN 'D’ Ottawa Ontario KIP 6P4 Canada Tokyo Gakugei University 4-1-1 Nukui-Kita-Maehi Koganei City Tokyo 184-8501 Japan

Dawazisaurus brevis（gen. et sp. nov.） is a newly discovered Triassic marine reptile, represented by a complete skeleton from Member II of the Guanling Formation of Luoping, Yunnan Province, China. This paper aims to（1） present a thorough description of the species,（2） make a detailed comparison to demonstrate if the species can be referred to any known sauropterygian taxa, and（3） conduct phylogenetic analyses to establish the internal relationships of the species with other sauropterygians. In addition, the discovery of Dawazisaurus provides a chance not only to test the phylogenetic patterns of the Sauropterygia obtained by previous studies but also to evaluate the previous hypotheses on the origin of the sauropterygian groups at different levels. D. brevis is an eosauropterygian, characterized by a unique combination of derived features such as a pair of large nasals joining in the formation of the internarial septum, a short trunk with 16 dorsal vertebrae; the zygapophyses of the trunk vertebrae very small or weakly developed; the posterior margin of the skull roof deeply V-shaped, and an ossified distal carpal 5. Phylogenetic analysis indicates that D. brevis appears to be more closely related to the Nothosauroidea than the Pistosauroidea within the Eosauropterygia.

关键词： Sauropterygia Dawazisaurus brevis Guanling Formation Early Triassic Yunnan China