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Infinitely many pairs of cospectral integral regular graphs

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Applied Mathematics(A Journal of Chinese Universities) 2011年第3期26卷 280-286页

作者： WANG Li-gong SUN hao Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China.

A graph G is called integral if all the eigenvalues of the adjacency matrix A（G） of G are integers. In this paper, the graphs G4（a, b） and Gs（a, b） with 2a ＋ 6b vertices are defined. We give their characteristic polynomials from matrix theory and prove that the （n ＋ 2）-regular graphs G4（n, n＋ 2） and G5（n, n ＋ 2） are a pair of non-isomorphic connected cospectral integral regular graphs for any positive integer n.

关键词： Eigenvalue integral graph cospectral graph graph spectrum.

Review of research on loosening of threaded fasteners

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Friction 2022年第3期10卷 335-359页

作者： hao gong Xiaoyu DING Jianhua LIU Huihua FENG School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Loosening of threaded fasteners is a key failure mode,which is mainly caused by the slippage and friction behaviors on the thread and bearing surfaces,and will affect the integrity and reliability of *** scholars have conducted research on the loosening of threaded fasteners;however,comprehensive reviews on the loosening of threaded fasteners have been *** this review article,we define loosening as a loss of preload and divide it into non-rotational and rotational *** causes and mechanisms of non-rotational and rotational loosening are *** essential topics regarding loosening under transverse vibration have also attracted significant attention and have been investigated widely,including the loosening curve,critical condition of loosening,and influencing factors of *** research carried out on these three topics is also summarised in this *** is believed that our work will not only help new researchers quickly understand the state-of-the-art research on loosening,but also increase the knowledge of engineers on this critical *** the future,it is important to conduct more quantitative research on local slippage accumulation,and the relationship between local slippage accumulation and rotational loosening,which will have the potential to comprehensively unravel the loosening mechanism,and effectively guide the anti-loosening design of threaded fasteners.

关键词： threaded fasteners loosening vibration loosening curve critical condition influencing factors

Concept of radial slippage propagation triggering self-loosening and optimisation design of novel anti-loosening structures

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Friction 2023年第6期11卷 865-880页

作者： hao gong Jianhua LIU Huihua FENG Jiayu HUANG Beijing Institute of Technology School of Mechanical EngineeringBeijing100081China

Self-loosening of bolted joints can occur in a vibration environment,and it may induce bolt fatigue fracture with catastrophic *** is essential to clarify the self-loosening mechanism,based on which novel anti-loosening thread structures can be *** this paper,we propose the concept of radial slippage propagation and provide new insights into the self-loosening *** new theory states that the slippage along the radial direction of the thread surface induces more slippage areas(slippage propagation),and self-loosening occurs due to the dynamic evolution and propagation of contact states on the thread and bearing surfaces with an increase in the number of vibration *** element analysis(FEA)was used to validate the propagation process of slippage areas on the thread surface.A novel bolted joint with step thread engagement was developed,which could prevent the occurrence of relative motion of the external and internal threads in the radial direction and thus block slippage propagation.A three-dimensional(3D)finite element model(FEM)of the novel thread structure was established,and a test specimen was manufactured using two special *** and experiments validated its superior anti-loosening and anti-fatigue performances,and the convenience of installation and *** validation of the radial slippage propagation theory and the performance optimisation of the step-thread structure should be performed in the future.

关键词： bolted joint self-loosening slippage propagation step thread transversal vibration

Heat Treatment of Spray Deposition SiCp/6066 Aluminum Matrix Composites

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Journal of Central South University 2000年第2期12卷 61-64页

作者： gong hao-ran Li Wen-xian Department of Materials Science and Engineering Central South University of TechnologyChangsha 410083China

Heat treatment of spray deposition 10% SiCp/6066 ( φ (SiCp)=10%) composites was investigated by means of hardness measurement. The results show that heat treatment technology is influenced by the presence of SiC particles. Compared with the base alloy 6066, the composites have lower burning temperature and is burnt at 540 ℃ due to the enrichment of Mg and Cu atoms in the SiCp/6066 interfaces. As a result, solution treatment of the composites should be carried out at lower temperature. The aging parameter values such as the aging temperature, the precipitation temperature of β′ and β phases, as well as the peak aging time, become lower. The optimum heat treatment process conditions are that the composites are solution treated at 515 ℃ and aged at 165 ℃ for 5 h.

关键词： spray deposition composites solution treatment temperature aging

Steady State Rheological Characteristic of Semisolid Magnesium Alloy

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Journal of Materials Science & Technology 2007年第5期23卷 637-640页

作者： Fengyun YAN Liping SUN Yi gong Yuan hao State Key Laboratory of Gansu Advanced Non-Ferrous Metal Materials Lanzhou University of Technology Lanzhou 730050 China

Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-1500D simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.

关键词： Semi-solid magnesium alloy Apparent viscosity Rheological characteristic Deformation resistance

Early peripheral perfusion index predicts 28-day outcome in patients with septic shock

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World Journal of Emergency Medicine 2024年第5期15卷 372-378页

作者： Cheng Chi hao gong Kai Yang Peng Peng Xiaoxia Zhang Department of Emergency Peking University People's HospitalBeijing 100044China Department of Emergency Intensive Care Unit the First Affi liated Hospital of Xinjiang Medical UniversityUrumqi 830000China

BACKGROUND:To investigate the prognostic value of the peripheral perfusion index(PPI)in patients with septic ***:This prospective cohort study,conducted at the emergency intensive care unit of Peking University People's Hospital,recruited 200 patients with septic shock between January 2023 and August *** patients were divided into survival(n=84)and death(n=116)groups based on 28-day *** evaluations included laboratory tests and clinical scores,with lactate and PPI values assessed upon admission to the emergency room and at 6 h and 12 h after *** factors associated with mortality were analyzed using univariate and multivariate Cox regression *** operator characteristic(ROC)curve was used to assess predictive *** rates were compared,and Kaplan-Meier survival plots were ***:Compared to the survival group,patients in the death group were older and had more severe liver damage and coagulation dysfunction,necessitating higher norepinephrine doses and increased fl uid *** lactate levels and lower PPI levels at 0 h,6 h,and 12 h were observed in the death *** Cox regression identifi ed prolonged prothrombin time(PT),decreased 6-h PPI and 12-h PPI as independent risk factors for *** area under the curves for 6-h PPI and 12-h PPI were 0.802(95%CI 0.742-0.863,P<0.001)and 0.945(95%CI 0.915-0.974,P<0.001),respectively,which were superior to Glasgow Coma Scale(GCS),Sequential Organ Failure Assessment(SOFA)scores(0.864 and 0.928).Cumulative mortality in the low PPI groups at 6 h and 12 h was signifi cantly higher than in the high PPI groups(6-h PPI:77.52%vs.22.54%;12-h PPI:92.04%vs.13.79%,P<0.001).CONCLUSION:PPI may have value in predicting 28-day mortality in patients with septic shock.

关键词： Peripheral perfusion index Septic shock Prognosis Predictive value

Improving the tensile properties of extruded Mg–Ga alloy by ageing treatment

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Progress in Natural Science:Materials International 2022年第6期32卷 724-731页

作者： Donglei He hao gong Ziyue Zhang Yang Zheng Hu Zhang Yan Li School of Materials Science and Engineering Beihang University Key Laboratory of Aerospace Advanced Materials and Performance (Beihang University) Ministry of Education School of Aeronautics and Astronautics Tiangong University Beihang Hangzhou Innovation Institute Yuhang Beihang University Beijing Advanced Innovation Centre for Biomedical Engineering Beihang University

A hot-extruded Mg-5Ga alloy was subjected to ageing treatment at 150℃,190℃ and 230℃.The microstructures and mechanical properties of the extruded and aged alloy were examined in this *** examinations suggested that particle-shaped and rod-shaped Mg5Ga2were precipitated in the alloy after peak ageing *** extruded alloy showed the yield strength,ultimate tensile strength and elongation to fracture of 157.6 MPa,248.6 MPa and 17.5%,*** peak ageing,the yield strength and ultimate tensile strength can be enhanced by as much as 15.7% and 8.6% reaching 182.3 MPa and 270 MPa,*** improvement of the tensile strengths is mainly attributed to the enhanced precipitation strengthening by newly formed fine *** ductility of the alloy was slightly increased by peak ageing at low temperatures(150℃ and 190 ℃),but remarkably decreased by peak ageing at high temperature(230℃) due to the formation of coarsened Mg5Ga2particles which easily initiated the cracks during tensile deformation.

关键词： Mg-Ga alloy Microstructure Mechanical property Ageing treatment

Ultra-long room temperature phosphorescence of indium-based organic inorganic metal halides for naked-eye-visible afterglow

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Science China Chemistry 2023年第9期66卷 2576-2582页

作者： Heng Yu hao gong Zhaorui Hua Yang Zhang Wenming Sun Shuyan gong Ganglong Cui Yang Tian Hongbing Fu Beijing Key Laboratory for Optical Materials and Photonic Devices Department of ChemistryCapital Normal UniversityBeijing 100048China Key Laboratory of Theoretical and Computational Photochemistry Ministry of EducationCollege of ChemistryBeijing Normal UniversityBeijing 100875China

Solid-state molecules based on room-temperature phosphorescent(RTP)emission have received extensive attention due to their special optical properties of triplet ***,there are still few solid molecular systems with naked-eye-visible afterglow ***,we introduce 4-phenylbenzylamine(namely PBA)with a long conjugated system into common non-toxic In^(3+)to form an indium-based organic inorganic halide,whose chemical formula is PBA_(3)[InCl_6]·H_(2)***,this hybrid halide generates a RTP emission at 617 nm with a lifetime decay as long as 290.4 ms,expressing a naked-eye-visible afterglow for more than 7 *** mechanism study shows that the long lifetime RTP originated from the specific lamellar stacking of organic molecules and metal halide units,facilitating the interaction between the inorganic layers and organic ***,the material can be potentially used in emergency lighting,information security,and other ***,this work provides a reference for the design and implementation of a more efficient organic-inorganic hybrid system with the ultralong RTP emission.

关键词： phosphorescence indium 4-phenylbenzylamine halide afterglow

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Martensitic transformation,shape memory effect and superelasticity of Ti-xZr-(30-x)Nb-4Ta alloys

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Rare Metals 2019年第10期38卷 965-970页

作者： Wen-Tao Qu hao gong Jun Wang Yong-Sheng Nie Yan Li School of Mechanical Engineering Xi'an Shiyou UniversityXi’an 710065China School of Materials Science and Engineering Beihang UniversityBeijing 100191China Beijing Advanced Innovation Centre for Biomedical Engineering Beihang UniversityBeijing 100191China Lanzhou Seemine SMA Co.Ltd Lanzhou 730010China

Martensitic transformations,mechanical properties,shape memory effect and superelasticity of Ti-xZr-(30-x)Nb-4Ta(x=15,16,17 and 18;at%) alloys were investigated.X-ray diffraction(XRD),optical microscopy(OM) and transmission electron microscopy(TEM) results indicated that the Ti-16Zr-14Nb-4Ta,Ti-17Zr-13Nb-4Ta and Ti-18Zr-12Nb4Ta alloys were mainly composed of α″-martensite,while the Ti-15Zr-15Nb-4Ta alloy was characterized by predominant p *** reverse martensitic transformation temperatures increased when Nb was replaced by Zr,indicating stronger p-stabilizing effect for the *** Ti-15Zr-15Nb-4Ta alloy displayed superelasticity during tensile deformation with a recovery strain of 3.51%.For the other three alloys with higher Zr content,the martensitic reorientation occurred during tensile deformation,resulting in shape memory recovery upon subsequent *** maximum shape memory effect was 3.46% in the Ti-18Zr-12Nb-4Ta alloy.

关键词： Ti-Zr alloys Martensitic transformation Shape memory effect Superelasticity