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A Result on Character Degrees and Conjugacy Class Sizes in Finite Groups

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Wuhan University Journal of Natural Sciences 2012年第4期17卷 277-280页

作者： chen sheng'an School of Mathematics and Statistics Central China Normal UniversityWuhan 430079HubeiChina School of Mathematics and Statistics Hubei University of Science and TechnologyXianning 437100HubeiChina

Let G be a finite group and π be a set of primes including at least two elements. We write cd（G） and cs（G） to denote the set of complex irreducible character degrees and conjugacy class sizes of G , respectively, and write π（m）to denote the set of all prime divisors of a positive integer m . For any 1≠m∈cd（G） and 1≠m∈cs（G）, in this note, we shall present the corresponding group structures of finite group G in the case π（m）=π , respectively, which generalizes the result of finite groups with character degrees of two distinct primes. Furthermore, we shall see that the influence of the two sets on the group structure is analogous.

关键词： character degrees conjugacy class sizes group structures

COMPOSITE ELEMENT MODEL FOR ROCK MASS SEEPAGE FLOW

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Journal of Hydrodynamics 2006年第2期18卷 219-224页

作者： chen sheng-hong FENG Xue-min State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072 China

In this paper, the algorithm developed on the concept of the Composite Element Method （CEM） is proposed for the seepage flow in discontinuous rock masses, The basic idea is that if an element contains one or more discontinuity segments, it will be denoted as a composite element having a set of hydraulic potential values defined at its nodes. By the variation principle, the governing equation can be established to solve the unknown hydraulic potential values at the composite element nodes. The main advantage of the proposed model is that the generation of calculation mesh will not be restricted strongly by the number, the position and the orientation of the discontinuities, A numerical example is presented at the end of the paper, to show the validity of the proposed model.

关键词： Composite Element Method(CEM) rock mass seepage flow

Mechanical and fatigue properties of SA508-Ⅳ steel used for nuclear reactor pressure vessels

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Journal of Iron and Steel Research International 2022年第8期29卷 1312-1321页

作者： Xin Dai Yue-feng chen Peng Wang Li Zhang Bin Yang Lian-sheng chen Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210HebeiChina

The mechanical and fatigue properties of SA508-Ⅳ steel with martensite and granular bainite, respectively, were studied. The mechanical tests results showed that the ultimate tensile strength and impact toughness of the specimen with martensite were 830 MPa and 158 J, respectively, and those of the specimen with granular bainite were 811 MPa and 115 J, respectively. The former had higher tensile strength and impact toughness than the latter. The impact tests results showed that the former belonged to typical dimple fracture, while the latter belonged to brittle fracture. The fatigue tests results showed that the fatigue life of the specimen with martensite was 2717 cycles, and that of the specimen with granular bainite was 1545 cycles under the strain amplitude of ± 0.45%. The specimen with martensite had fewer crack initiation points, narrower fatigue striations separation, and larger volume fraction of high-angle grain boundaries than the latter. The fewer crack initiation points meant fewer fatigue cracks, the narrower fatigue striations separation meant slower crack propagation rate, and the larger volume fraction of high-angle grain boundaries could more effectively hinder fatigue crack propagation. Based on these facts, the fatigue life of the specimen with martensite was higher than that of the specimen with granular bainite.

关键词： Nuclear reactor pressure vessel SA508-Ⅳsteel Low cycle fatigue Crack initiation Crack propagation

Palladium-Catalyzed Cross-Coupling of Fluorinated Vinyl Chlorides with Terminal Alkynes： A General Protocol to Fluorinated Enynes

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Chinese Journal of Chemistry 2013年第7期31卷 901-907页

作者： sheng chen Chunfa Xu Long Lu Qilong Shen Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China

An efficient and cost-effective method for the preparation of fluorinated conjugated enynes was described, tile method was compatible with a variety of functional groups such as chloride, amine, cyano and ester group. The method could also be extended to the coupling of （R,Z）-3-（2-chloro-1,2-difluorovinyl）-4-alkyloxazolidin-2-one （3） with moderate yields.

关键词： fluorine enyne palladium chlorotrifluoroethylene

Hom-Gel'fand–Dorfman Super-bialgebras and Hom-Lie Conformal Superalgebras

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Acta Mathematica Sinica,English Series 2017年第1期33卷 96-116页

作者： La Mei YUAN sheng chen Cai Xia HE Academy of Fundamental and Interdisciplinary Sciences Harbin Institute of Technology Harbin 150080 P. R. China Department of Mathematics Harbin Institute of Technology Harbin 150001 P. R. China

The aim of this paper is to introduce and study Hom-Gel＇fand-Dorfman super-bialgebras and Hom-Lie conformal superalgebras. In this paper, we provide different ways for constructing Hom- Gel＇fand-Dorfman super-bialgebras. Also, we obtain some infinite-dimensional Hom-Lie superalgebras from affinization of Hom-Gel＇fand-Dorfman super-bialgebras. Finally, we give a general construction of Hom-Lie conformal superalgebras from Hom-Lie superalgebras and establish the equivalence between quadratic Hom-Lie conformal superalgebras and Hom-Gel＇fand-Dorfman super-bialgebras.

关键词： Lie conformal superalgebra Horn-Lie superalgebra Hom-Lie conformal superalgebra,Hom-Gel'fand-Dorfman super-bialgebra

The Superiorities of Bayes Linear Unbiased Estimator in Multivariate Linear Models

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Acta Mathematicae Applicatae Sinica 2012年第2期28卷 383-394页

作者： Wei-ping ZHANG Lai-sheng WEI Yu chen Department of Statistics and Finance University of Science and Technology of China Hefei 230026 China

In this article, the Bayes linear unbiased estimator （BALUE） of parameters is derived for the multivariate linear models. The superiorities of the BALUE over the least square estimator （LSE） is studied in terms of... 详细信息

关键词： multivariate linear models Bayes linear unbiased estimator least square estimator mean squareerror matrix criterion Bayesian Pitman closeness criterion

A simplified physically-based breach model for a high concrete-faced rockfill dam:A case study

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Water Science and Engineering 2018年第1期11卷 46-52页

作者： Qi-ming Zhong sheng-shui chen Zhao Deng Department of Geotechnical Engineering Nanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-rock Dam of the Ministry of Water Resources Nanjing 210024China

A simplified physically-based model was developed to simulate the breaching process of the Gouhou concrete-faced rockfill dam （CFRD）, which is the only breach case of a high CFRD in the world. Considering the dam height, a hydraulic method was chosen to simulate the initial scour position on the downstream slope, with the steepening of the downstream slope taken into account; a headcut erosion formula was adopted to simulate the backward erosion as well. The moment equilibrium method was utilized to calculate the ultimate length of a concrete slab under its self-weight and water loads. The calculated results of the Gouhou CFRD breach case show that the proposed model provides reasonable peak breach flow, final breach width, and failure time, with relative errors less than 15% as compared with the measured data. Sensitivity studies show that the outputs of the proposed model are more or less sensitive to different parameters. Three typical parametric models were compared with the proposed model, and the comparison demonstrates that the proposed physically-based breach model performs better and provides more detailed results than the parametric models.

关键词： Concrete-faced rockfill dam Physically-based breach model Parametric breach model Sensitivity analysis Gouhou CFRD

Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

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Communications in Theoretical Physics 2009年第2期51卷 287-292页

作者： LI Liang-sheng LI Li chen Xiao-Song Institute of Theoretical Physics Chinese Academy of Sciences P.O. Box 2735 Beijing 100190 China

The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation （MF）. The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density p＊=pσ3=0.224 and the reduced temperature T＊ =kT/ε=1.87 （σ is the diameter of Heisenberg hard sphere and e is the coupling constant）.

关键词： critical phenomena order-disorder magnetic liquid

Numerical model for homogeneous cohesive dam breaching due to overtopping failure

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Journal of Mountain Science 2017年第3期14卷 571-580页

作者： ZHONG Qi-ming chen sheng-shui DENG Zhao Department of Geotechnical Engineering Nanjing Hgdraulic Research InstituteNanjing 210024China Nanjing Hgdraulic Research Institute Nanjing 210029China Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-rock Dam of the Ministry of Water Resources Nanjing 210029China

Based on the large-scale model tests, a simplified dam breach model for homogeneous cohesive dam due to overtopping failure is put forward. The model considers headcut erosion as one of the key homogeneous cohesive dam breaching mechanisms and we calculate the time-averaged headcut migration rate using an energy-based empirical formula. A numerical method is adopted to determine the initial scour position at the downstream slope in terms of the water head and dam height, and the broad-crested weir equation is utilized to simulate the breach flow. The limit equilibrium method is used to analyze the stability of breach slope during the breach process. An iterative method is developed to simulate the coupling process of soil and water at each time step. The calculated results of three dam breach cases testify the reasonability of the model, and the sensitivity studies of soil erodibility show that sensitivity is dependent on each test case's soil conditions. In addition, three typical dam breach models, NWS BREACH, WinDAM B, and HR BREACH, are also chosen to compare with the proposed model. It is found that NWS BREACH may have large errors for cohesive dams, since it uses a noncohesive sediment transport model and does notconsider headcut erosion, WinDAM B and HR BREACH consider headcut erosion as the breaching mechanism and handle well homogeneous cohesive dam overtopping failure, but overall, the proposed model has the best performance.

关键词： KeHomogeneous cohesive dam Overtopping Headcut Initial scour position Sensitivity analysis Models comparison