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Mathematical Models and Computer Simulation of Nitrogen Concentration Profiles in Pulse Plasma Nitrided Layers

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Journal of Materials Science & Technology 2003年第z1期19卷 164-166页

作者： Mufu yan Qingchang meng Jihong yan Harbin Institute of Technology Harbin 150001 China Harbin Institute of Technology Harbin 150001 China Harbin Institute of Technology Harbin 150001 China

Two materials, pure Fe and pure Al, were nitrided in a pulse plasma nitriding facility. The nitrogen profiles in surface layers and the surface phase structures of specimens nitrided at 500℃ for 8 h for Fe and for 6 h for Al were measured using the glow discharge spectrometry and an X-ray diffractometer, respectively. XRD results indicate that the compound layer with hcp crystal structure (AIN) was formed on the top of Al substrate. During nitriding of Fe, the compound layer growth conforms to parabolic law and the surface nitrogen concentration change little with increasing the nitriding time. The surface nitrogen content of nitrided Al specimens is less than theoretical value 34.17 wt pct of AIN. The mathematical models of nitrogen concentration profiles in the surface layer of nitrided Al specimen have been established based on the research of the kinetics of pulse plasma nitriding of Fe and the nitrogen concentration profiles were also simulated. Results show that the predicted curves agree basically with the experimental data.

关键词： Pulse plasma nitriding, Nitrogen concentration profile, Computer simulation

Estimates for multUinear singular integral operators with nonsmooth kernels

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Frontiers of Mathematics in China 2012年第1期7卷 51-67页

作者： Guoen HU yan meng Department of Applied Mathematics Zhengzhou Information Science and TechnologyInstitute Zhengzhou 450002 China School of Information Renmin University of China Beijing 100872 China

Let （H,d,μ） be a space of homogeneous type in the sense of Coifman and Weiss. In this paper, we consider the behavior on Lp^p1 （X） x ... x LP^m（X） for the m-linear singular integral operators with nonsmooth ker... 详细信息

关键词： Approximation to the identity multilinear singular integraloperator nonsmooth kernel

Multilinear Calderón-Zygmund Operator on Products of Hardy Spaces

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Acta Mathematica Sinica,English Series 2012年第2期28卷 281-294页

作者： Guo En HU yan meng Department of Applied Mathematics Zhengzhou Information Science and Technology InstituteP.0.Box 1001-747.Zhengzhou 450002.P.R.China School of Information Renmin University of ChinaBeijing 100872P.R.China

In this paper, the authors establish the boundedness of the multilinear Calderon-Zygmund operator from products of Hardy spaces into Hardy spaces

关键词： Multilinear Calderdn-Zygmund operator Hardy space atomic decomposition

Weighted estimates for iterated commutators of multilinear Calderón-Zygmund operators on non-homogeneous metric measure spaces

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Science China Mathematics 2021年第3期64卷 519-546页

作者： Yuan Zhao Haibo Lin yan meng College of Science China Agricultural UniversityBeijing 100083China School of Mathematics Renmin University of ChinaBeijing 100872China

Let(X, d, μ) be a non-homogeneous metric measure space satisfying the so-called upper doubling and geometrically doubling conditions, which includes the space of homogeneous type and the Euclidean space with the non-doubling measure as special cases. Let T be a multilinear Calderón-Zygmund operator and b:=(b1,..., bm) be a finite family of RBMO(μ) functions. In this paper, some weak-type multiple weighted estimates for the iterated commutator T∏bgenerated by T and b are obtained.

关键词： non-homogeneous metric measure space multiple weight commutator multilinear Calderón-Zygmund operator

A New Function Space from Barron Class and Application to Neural Network Approximation

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Communications in Computational Physics 2022年第10期32卷 1361-1400页

作者： yan meng Pingbing Ming School of Mathematics Renmin University of ChinaBeijing 100872China LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAMSSChinese Academy of SciencesNo.55East Road Zhong-Guan-CunBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China.

We introduce a new function space,dubbed as the Barron spectrum space,which arises from the target function space for the neural network *** give a Bernstein type sufficient condition for functions in this space,and clarify the embedding among the Barron spectrum space,the Bessel potential space,the Besov space and the Sobolev ***,the unexpected smoothness and the decaying behavior of the radial functions in the Barron spectrum space have been *** an application,we prove a dimension explicit L^(q) error bound for the two-layer neural network with the Barron spectrum space as the target function space,the rate is dimension independent.

关键词： Fourier transform Besov space Sobolev space radial function neural network

High temperature lubrication performance of chlorophenyl silicone oil

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Friction 2024年第8期12卷 1716-1727页

作者： yan meng Xiangli WEN Jie CHENG Pengpeng BAI Yonggang meng Yu TIAN School of Mechanical and Electrical Engineering China University of Mining and Technology-BeijingBeijing 100083China Department of Mechanical Engineering State Key Laboratory of Tribology in Advanced EquipmentTsinghua UniversityBeijing 100084China

Most studies of liquid lubricants were carried out at temperatures below 200°***,the service temperature of lubricants for aerospace and aeroengine has reached above 300°*** order to investigate the friction mechanism and provide data for high temperature lubrication,the friction and wear properties of chlorophenyl silicone oil(CPSO)-lubricated M50 steel and Si3N4 friction pairs were investigated ***-on-disk experimental results show that the lubrication performance of CPSO varies significantly with *** 150°C,coefficient of friction(COF)remains at 0.13–0.15 after the short running-in stage(600 s),while the COF in the running-in stage is 0.2–*** 200°C and above,the running-in time is much longer(1,200 s),and the initial instantaneous maximum COF can reach *** this condition,the COF gradually decreases and finally stabilizes at around 0.16–0.17 *** phenomenon is mainly due to the different thickness of boundary adsorption *** importantly,the wear rate of M50 steel increases significantly with the temperature,while the wear rate barely changes at temperatures above 200°*** anti-wear mechanism is explained as tribochemical reactions are more likely to occur between CPSO and steel surface with the increased temperature,generating the FeCl2 protective film on the metal ***,FeCl2 tribochemical film improves the lubrication and anti-wear capacity of the *** high temperatures(200–350°C),FeCl2 film becomes thicker,and the contact region pressure becomes lower due to the larger wear scar size,so the wear rate growth of M50 steel is much smaller compared with that of low temperatures(22–150°C).The main findings in this study demonstrate that CPSO lubricant has good anti-wear and lubrication capacity,which is capable of working under temperatures up to 350°C.

关键词： chlorophenyl silicone oil(CPSO) liquid lubricant anti-wear high temperature

Boundedness of Commutators with Lipschitz Functions in Non-homogeneous Spaces

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Chinese Annals of Mathematics,Series B 2007年第1期28卷 67-80页

作者： Xiaoli FU yan meng Dachun yanG School of Mathematical Sciences Beijing Normal University Beijing 100875 China School of Information Renmin University Beijing 100872 China Corresponding author. School of Mathematical Sciences Beijing Normal University Beijing 100875 China

Under the assumption that the underlying measure is a non-negative Radon measure which only satisfies some growth condition, the authors prove that for a class of commutators with Lipschitz functions which include commutators generated by Calderon-Zygrnund operators and Lipschitz functions as examples, their boundedness in Lebesgue spaces or the Hardy space H^1 （μ） is equivalent to some endpoint estimates satisfied by them. This result is new even when the underlying measure μ is the d-dimensional Lebesgue measure.

关键词： Commutator Lipschitz function Lebesgue space Hardy space RBMO space Non-doubling measure

Internal force and deformation matrixes and their applications in load path

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第8期11卷 563-570页

作者： Qi CHEN Xin-jian KOU yan-meng ZHANG Department of Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China

This paper deals with the internal force and the deformation matrixes, both of which can be used to analyze the topological relationship of a structure. Based on the reciprocal theorem, the relationship between the two matrixes is established, which greatly simplifies the computation of the internal force matrix. According to the characteristics of the internal force matrix, the transfer law of the matrix itself (due to the removal of components) is established based on the principle of linear superposition. With the relation of the two matrixes, the transfer law of the deformation matrix is also obtained. The transfer law illuminates the change regularity of internal force or deformation of the remnant structure when certain members are cut off one after another. The results of numerical examples show that the proposed methods are correct, reliable and effective.

关键词： Truss structure Redundancy Robustness Topological relationship of structure Removal of members Transfer law

The evolving CRISPR technology

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Protein & Cell 2019年第11期10卷 783-786页

作者： meng yan Jinsong Li State Key Laboratory of Cell Biology Shanghai Key Laboratory of Molecular AndrologyCAS Center for Excellence in Molecular Cell ScienceShanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesUniversity of Chinese Academy of SciencesShanghai 200031China

Adva nces in genome editi ng tech no logy have revoluti on ized basic and applied biology research in recent years,particu?larly due to the newly emerged CRISPR/Cas technique(Ren et al.,2017b).The classical CRISPR/Cas system was derived from a bacterial defense system,which consists of a single guide RNA(sgRNA)for precise targeting and one Cas protein for DNA binding and nuclease *** on high precision of CRISPR/Cas system,multiple functions have been exploited in addition to original nuclease activity,such as genome base editing,gene knock-down and activation,chromatin imaging systems etc.

关键词： CRISPR/Cas nuclease system