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Journal of Materials Science & Technology 2019年第6期35卷 1099-1107页

作者： x.y. Jiao J. Wang C.F. Liu Z.P. guo G.D. Tong S.L. Ma y. Bi y.F. Zhang S.M. xiong School of Materials Science and Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Automobile Safety and Energy Tsinghua University Beijing China China FAW Foundry Co. Ltd. Changchun 130011. China

The fracture behavior of high-pressure die-cast hypereutectic(HPDC) Al-Si alloys was investigated using a high-resolution laboratory CT and synchrotron x-ray tomography with a particular focus on the influence of HPDC microstructure. Results showed that microstructure of the alloy was mainly comprised of primary silicon particles(PSPs), Al dendrites, Cu-rich phases and pores. Most of the coarse PSPs, Cu-rich phases and pores were located in the center of the specimen. The rapid solidification of HPDC led to a heterogeneous microstructural feature. Elemental Cu was enriched in the frontiers of solid-liquid interface, causing the formation of large size dendritic arms. The pores were formed in the interdendrites which endured high stress intensity under high applied stress. Microcracks were originated from pores and further connected Cu-rich phases causing intergranular fracture. PSPs worked as obstacles causing piling-up dislocations in the phase interface. In the regions where large size of PSPs enriched in, PSPs ruptured rather than debonded from matrix, indicating transgranular fractures of PSPs. Microcracks originated around pores and PSPs tended to converge on the main cracks to decrease the energy required for crack propagation.

关键词： Hypereutectic Al-Si alloy Primary silicon particles Porosity Fracture morphology High pressure die casting

Microstructure and Properties of WC-Co/NiCrBSi Brazing Coating

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Journal of Materials Science & Technology 1999年第3期15卷 283-285页

作者： Lu, SP guo, y Chen, LS Acad Sinica Inst Met Res Shenyang 110015 Peoples R China

Through rolling technology, a flexible metal cloth consisting of metal powder (NiCrBSi powder or WC-Co powder) and organism in a certain ratio were made, which could be used as brazing coating raw materials. WC-Co/NiCrBSi wear coating was fabricated through high temperature vacuum brazing after the flexible metal clothes were assembled on 42CrMo steel surface. The tensile strengths of coating self and coating/matrix approached to 100 similar to 140 MPa and 300 similar to 360 MPa, respectively, at different brazing parameters. Effect of Co on the wear property of the coating was analyzed. The abrasive wear property of WC-Co/NiCrBSi brazing coating is better than WC-17Co/NiCrBSi flame overlaying and CoCrW overlaying.

关键词： WC Co Microstructure and Properties of WC-Co/NiCrBSi Brazing Coating

Simulation of Dynamic 3D Crack Propagation within the Material Point Method

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Computer Modeling in Engineering & Sciences 2017年第4期113卷 389-410页

作者： y.J.guo J.A.Nairn Univ.of Utah Salt Lake CityUT 84112USA2119 Hillside Oak LnHoustonTX 77062USA Wood Science&Engineering Oregon State UniversityCorvallisOR 97330USA

This paper presents the principles and algorithms for simulation of dynamic crack propagation in elastic bodies by the material point method(MPM),from relatively simple two-dimensional cases to full three-dimensional,mixed-mode crack *** paper is intended to give a summary of the latest achievements on simulation of three-dimensional dynamic crack propagation,which is essentially an unexplored *** of the methodology presented in this paper to several dynamic crack propagation problems has shown that the MPM is a reliable and powerful approach for simulating three-dimensional,mixed-mode crack propagation.

关键词： Material point method (MPM) dynamic fracture crack propagation threedimensional cracks mixed-mode

Metabolome and RNA-seq reveal discrepant metabolism and secretory metabolism profile in skeletal muscle between obese and lean pigs at different ages

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Science China Life Sciences 2025年

作者： Liu guo Junfei xu Wenyue Zhou Sisi Chen Hanjing Shi Mengmeng Han Zekun yang yehui Duan Weijun Pang yulong yin Fengna Li Laboratory of Animal Nutritional Physiology and Metabolic Process Key Laboratory of Agro-ecological Processes in Subtropical Region Institute of Subtropical Agriculture Chinese Academy of Sciences University of Chinese Academy of Sciences Laboratory of Animal Fat Deposition and Muscle Development College of Animal Science and Technology Northwest A&F University College of Advanced Agricultural Sciences University of Chinese Academy of Sciences

Metabolites and metabolism-related gene expression profiles in skeletal muscle change dramatically under obesity, aging and metabolic disease. Since obese and lean pigs are ideal models for metabolic research. Here, we compared metabolome and transcriptome of Longissimus dorsi(LD) muscle between Taoyuan black(TB, obese) and Duroc(lean) pigs at different ages. We defined the “window phase” of intramuscular fat(IMF) deposition in TB pig, which has significantly higher IMF than Duroc pig. Our results displayed discrepant lipid composition and different expression genes(DEGs) enriched in lipid metabolism, and both metabolome and transcriptome analyses revealed stronger energy expenditure and more active amino acid and protein metabolism in Duroc pig. 10 up-and 51 down-regulated biomarker metabolites with age-and breed-specificity were identified. Potential secretory metabolites, including organic acid(fumaric acid, succinate,malic acid, and gamma-aminobutyric acid), amino acid(L-lysine, and L-glutamic acid), lipid(2-hydroxyisovaleric acid, and L-carnitine) were demonstrated a significant correlation with IMF deposition. Our research highlights the huge difference of metabolic spectrum in skeletal muscle between obese and lean model and muscle-derived secretory metabolites might act as an ambassador of intercellular communication to regulate systematic metabolism.

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Development of dipole magnet power supply for BEPC-II energy upgrading project

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Radiation Detection Technology and Methods 2019年第2期3卷 32-36页

作者： x.L.guo B.Chen C.Han y.Gao University of Chinese Academy of Sciences Beijing 100049China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Dongguan Neutron Science Center Dongguan 523803China

Purpose In order to make BEPC-II to run at a higher energy,the Institute of High Energy Physics undertook an upgrading *** of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies;therefore,these four magnet power supplies are developed for the BEPC-II *** The power supplies adopt topologies of thyristor rectifiers to realize a high-power *** the control unit of each power supply,a digital current closed loop is adopted,and the key components in the feedback loop are thermostatically *** order to improve the performances of the power supplies,analog voltage regulators are added to the inner control *** These four power supplies have been tested and have already been officially used in BEPC-II,and their powers have reached the requirements of the *** test results of the current stability are described and shown in this paper,which testifies that the stabilities meet the design *** A digital control is applied to each SCR rectifier *** performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops,which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.

关键词： SCR rectifier Dipole magnet power supply Stability BEPC-II

Solution procedure of residue harmonic balance method and its applications

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Science China(Physics,Mechanics & Astronomy) 2014年第8期57卷 1581-1591页

作者： guo ZhongJin LEUNG A y T MA xiaoyan School of Mathematics and Statistics Taishan University Department of Civil and Architectural Engineering City University of Hong Kong

This paper presents a simple and rigorous solution procedure of residue harmonic balance for predicting the accurate approximation of certain autonomous ordinary differential *** this solution procedure,no small parameter is *** harmonic residue of balance equation is separated in two parts at each *** first part has the same number of Fourier terms as the present order of approximation and the remaining part is used in the subsequent *** corrections are governed by linear ordinary differential equation so that they can be solved easily by means of harmonic balance method *** kinds of different differential equations involving general,fractional and delay ordinary differential systems are given as numerical examples *** accurate limited cycle frequency and amplitude are *** results match well with the exact solutions or numerical solutions for a wide range of control *** with those available shows that the residue harmonic balance solution procedure is very effective for these autonomous differential ***,the present method works not only in predicting the amplitude but also the frequency of bifurcated period solution for delay ordinary differential equation.

关键词： residue harmonic balance accurate approximation fractional ordinary differential system delay ordinary differential system

STUDy ON THE SURFACE MODIFICATION OF NANOMETER CARBON PARTICLES IN ATMOSPHERIC PLASMA

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Acta Metallurgica Sinica(English Letters) 2002年第2期15卷 177-181页

作者： y.J. Ge, G.Q. Zhang, y.M. Liu, x.G. guo and Z.F. Zhao Beijing Institute of Printing, Beijing 102600, China Beijing Institute of Printing Beijing 102600China

The surface modification of nanometer carbon material has been studied by using an Induced Dielectric Barrier Discharge Plasma device (IDBD). The experimental results show that with different work gases and different discharge conditions, the surface behaviors of carbon black can be changed according to needs, including the use of different functional groups and the change of the surface roughness of carbon particles etc., which increased the grinding and dispersion abilities in binder.

关键词： surface modification. nanometer material IDBD plasma. carbon black

Molecular　Dynamics　Simulation　on　Thermodynamic　Properties　and　Transport　Coefficients

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Journal of Thermal Science 1996年第3期5卷 196-200页

作者： D.x. xiong y.S. xu, Z.y. guo (Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China) Department of Engineering Mechanics Tsinghua University Beijing China

Molecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential. The results on the velocity distribution,mean free path, mean collision time, specific heat and self-diffusion coefficient agree well with the existing theoretical/ experimental data. It shows that molecular dynamics method is another bridge to connect microworld and macroworld.

关键词： molecular dynamics simulation thermodynamic property transport coefficient

MICROSTRUCTURES AND PROPERTIES OF RECIPROCATINGLy ExTRUDED Mg-6.4Zn-1.1y ALLOyS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： Z.M. Zhang C.J. xu x.F. guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral Mg3 yZn6 quasicrystalline phase can be produced in Mg-Zn- y system alloys when a proper amount of Zn and y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast Mg-6.4Zn-1.1 y alloy are analyzed. The microstructure of the as-cast Mg-6.4Zn-1.1 y alloy consists of the α-Mg solid solution, icosahedral Mg3yZn6 quasicrystal, and Mg3 y2Zn3 and MgZn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, Mg3 y2 Zn3 and MgZn2 phases dissolved into the matrix, whereas, Mg3 yZn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 MPa, 258.2 MPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast Mg-6.4Zn-1.1 y alloy, particularly for elongation. The high performance of the Mg-6.4Zn-1.1 y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion Mg-Zn- y alloy Icosahedral quasicrystal

MICROSTRUCTURE OF Mg-6.4Zn-1.1y ALLOy FABRICATED By RAPID SOLIDIFICATION AND RECIPROCATING ExTRUSION

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 30-36页

作者： Z.M. Zhang C.J. xu x.F. guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1 y magnesium alloy with a thickness of 50-60μm were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by xRD. Phase transformation and its onset temperature were determined by differential thermal analyzer （DTA）. The analysis result shows that rapid solidification for *** alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in α-Mg solute solution, and impede the formation of Mg3 y2Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3 yZn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the α-Mg solid solution and icosahedral Mg3 yZn6 quasicrystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3 yZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases： α- magnesium solid solution as matrix and fine icosahedral Mg3 yZn6 quasicrystal which disperses uniformly in the matrix.

关键词： Magnesium alloy Rapid solidification Reciprocating extrusion Quasicrystal