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tHE CONVERGENCE OF MULtIGRID MEtHODS FOR SOLVING FINItE ELEMENt EQUAtIONS IN tHE PRESENCE OF SINGULARItIES

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Journal of Computational Mathematics 1995年第4期13卷 315-324页

作者： y.Q. huang y.X. Li(Depariment of Mathematics, Xiangtan University, Hunan, China) XIANGtAN UNIV DEPT MATHXIANGTANHUNANPEOPLES R CHINA

We analyze the convergence of multigrid methods applied to finite elementequations of second order with singularities caused by reentrant angles and abruptchanges in the boundary conditions. Provided much more weaker demand of clas-sical multigrid proofs, it is shown in this paper that, for symmetric and positivedefinite problems in the presence of singularities, multigrid algorithms with evenone smoothing step converge at a rate which is independent of the number of lev-els or unknowns. Furthermore, we extend this result to the nonsymmetric andindefinite problems.

关键词： Pro tHE CONVERGENCE OF MULtIGRID MEtHODS FOR SOLVING FINItE ELEMENt EQUAtIONS IN tHE PRESENCE OF SINGULARItIES

Enhanced and asymmetric signatures of hybridization at climatic margins: Evidence from closely related dioecious fig species

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Plant Diversity 2024年第2期46卷 181-193页

作者： Jian-Feng huang Clive t.Darwell yan-Qiong Peng CAS Key Laboratory of tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China National Center for Genetic Engineering and Biotechnology(BIOtEC) 113 Thailand Science ParkPhahonyothin RoadKhlong NuengKhlong LuangPathum Thani 12120Thailand

Hybridization plays a significant role in biological evolution. However, it is not clear whether ecological contingency differentially influences likelihood of hybridization, particularly at ecological margins where parental species may exhibit reduced fitnesses. Moreover, it is unknown whether future ecosystem change will increase the prevalence of hybridization. Ficus heterostyla and F. squamosa are closely related species co-distributed from southern thailand to southwest China where hybridization, yielding viable seeds, has been documented. As a robust test of ecological factors driving hybridization, we investigated spatial hybridization signatures based on nuclear microsatellites from extensive population sampling across a widespread contact range. Both species showed high population differentiation and strong patterns of isolation by distance. Admixture estimates exposed asymmetric interspecific gene *** of hybridization increase significantly towards higher latitude zones, peaking at the northern climatic margins. Geographic variation in reproductive phenology combined with ecologically challenging marginal habitats may promote this phenomenon. Our work is a first systematic evaluation of such patterns in a comprehensive, latitudinally-based clinal context, and indicates that tendency to hybridize appears strongly influenced by environmental conditions. Moreover, that future climate change scenarios will likely alter and possibly augment cases of hybridization at ecosystem scales.

关键词： Hybridization Heterospecific visitation Fig Pollinator wasp Asymmetric gene flow

Relationship between Primary Crystal temperature and Carbon Equivalent in Cast Iron

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Journal of Materials Science & technology 2008年第3期24卷 325-326页

作者： t.Kanno t.Kikuchi K.Hayashi y.Maruyama Kimura Chuzosho Co.Ltd. 1157 Nagasawa Shimizu-choShizuoka-ken

CE （=%C＋（1/3）x（%Si）） does not suit experiment results in many cases. In this work, the effect of alloy elements on primary crystal temperature was measured and the relationship between primary crystal temperature （tc） and carbon equivalent （CEL） was investigated. the results show that tc （Celsius degree） = 1650-110 × （%C） -25 × （%Si）＋3 × （%Mn） -35 × （%P） -71 × （%5）-2 × （%Ni） -7 × （%Cr）; CEL=%C ＋ 0.23×（%Si）-0.03× （%Mn）＋0.32×（%P）＋0.64×（%S）＋0.02×（%Ni）＋0.06×（%Cr）. that is, in hypo eutectic composition, carbon equivalent should be calculated with CEL=%C＋ 0.23×（%Si）, not with CE=%C＋（1/3） x（%Si）.

关键词： Carbon equivalent Cast iron Primary crystal temperature Hypo eutectic composition

Effect of sample size on the response of DEM samples with a realistic grading

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Particuology 2014年第4期12卷 107-115页

作者： Xin huang Kevin J.Hanley Catherine O'Sullivan Fiona C.y.Kwok Skempton Building Department of Civil and Environmental EngineeringImperial College LondonLondon SW7 2AZUnited Kingdom Haking Wong Building Department of Civil EngineeringThe University of Hong Kong

this paper shows that for DEM simulations of triaxial tests using samples with a grading that is repre- sentative of a real soil, the sample size significantly influences the observed material response. Four DEM samples with identical initial states were produced： three cylindrical samples bounded by rigid wails and one bounded by a cubical periodic cell, When subjected to triaxial loading, the samples with rigid boundaries were more dilative, stiffer and reached a higher peak stress ratio than the sample enclosed by periodic boundaries. For the rigid-wall samples, dilatancy increased and stiffness decreased with increasing sample size, the periodic sample was effectively homogeneous, the void ratio increased and the contact density decreased close to the rigid walls, this heterogeneity reduced with increasing sample size. the positions of the critical state lines （CSLs） of the overall response in e-log p＇ space were sensitive to the sample size, although no difference was observed between their slopes. the critical states of the interior regions of the rigid-wall-bounded samples approached that of the homogeneous periodic sample with increasing sample size. the ultimate strength of the material at the critical state is independent of sample size.

关键词： Discrete element method Sample size Rigid boundary Periodic boundary Critical state

tRANSFERMAtRIXMEtHODOFDAMPINGMULtIBODySyStEMSVIBRAtION

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宇航学报 1996年第2期 29-36页

作者：Ｅ．ＳｔｅｉｎＹ．Ｊ．ＨｕａｎｇＵｎｉｖｅｒｓｉｔａｔＨａｎｎｏｖｅｒ

基于文献［１，２］建立的多体系统传递矩阵法，进一步阐述了处理含有各种阻尼的多体系统固有振动的传递矩阵法，讨论了系统对任意激励响应

关键词：刚体弹性体阻尼多体系统传递矩阵法

SyNtHESIS AND SOLID StAtE SINtERING OF W-Ni-Fe NANO-COMPOSItE POWDERS

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Acta Metallurgica Sinica(English Letters) 2000年第3期13卷 917-920页

作者： Qu, X.H. Fan, J.L. Li, y.M. huang, B.y. Central South Univ of technology Changsha China

the mixture of 90 wt%W, 7 wt%Ni and 3 wt%Fe elemental powders was milled in a planetary high-energy ball mill. the evolution of the structure during milling and the sintering behavior of the milled powders were tested. the results showed that by mechanical alloying W(Ni, Fe) supersaturated solid solution with nano-meter size formed, which can enhance the sintering process. Fully dense alloy from the milled powders was obtained through solid state sintering. the tensile strength of the obtained alloy is over 900 MPa which is comparable to that of the alloy sintered by traditional liquid-phase sintering from un-milled powders of the same composition.

关键词： tungsten alloys Nickel alloys Iron alloys Mechanical alloying Powder metals Sintering Morphology tensile strength

Electrodeposition mechanism of Ni-Mo-P alloy in the solution of ammoniac citrate

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Chinese Journal of Chemistry 1997年第3期15卷 193-200页

作者： Zeng, y yao, SW Cao, XQ huang, HX Zhong, Zy Guo, Ht tIANJIN UNIV DEPT APPL CHEMTIANJIN 300072PEOPLES R CHINA

the induced codeposition mechanism of Mo, P and Ni from the solution of ammoniac citrate was studied by means of steady-state polarization, AC impedance and X-ray Photoelectron Spectroscopy (XPS). the result of electrochemical measurements proved that [NiCit(NH3)(2)](-) is the electro-active species of nickel, though nickel ions exist mainly as [NiCit(NH3)(3)](-) in ammoniac citrate. XPS experiments proved the existence of tetravalent molybdenum corresponding to MoO2 on the surface of some deposits. the intermediate product, MoO2, was probably reduced to Mo in the alloy deposit by atomic hydrogen adsorbed on the induced metal nickel. the reduction of H2PO2- occurs through two distinctive steps with PH3 as an, intermediate, which subsequently reacts with atomic hydrogen to form P in the alloy deposit. the electrodeposition mechanism was proposed in this paper.

关键词： Ni-Mo-P alloy electrodeposition mechanism

Frequency-domain L2-stability conditions for time-varying linear and nonlinear MIMO systems

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Control theory and technology 2014年第1期12卷 13-34页

作者： Zhihong huang y. V. VENKAtESH Cheng XIANG tong Heng LEE Department of Electrical & Computer Engineering National University of Singapore Singapore

the paper deals with the g2-stability analysis of multi-input-multi-output （MIMO） systems, governed by integral equations, with a matrix of periodic/aperiodic time-varying gains and a vector of monotone, non-monotone and quasi-monotone nonlin- earities. For nonlinear MIMO systems that are described by differential equations, most of the literature on stability is based on an application of quadratic forms as Lyapunov-function candidates. In contrast, a non-Lyapunov framework is employed here to derive new and more general g2-stability conditions in the frequency domain. these conditions have the following features： i） they are expressed in terms of the positive definiteness of the real part of matrices involving the transfer function of the linear time-invariant block and a matrix multiplier function that incorporates the minimax properties of the time-varying linear/nonlinear block, ii） For certain cases of the periodic time-varying gain, they contain, depending on the multiplier function chosen, no restrictions on the normalized rate of variation of the time-varying gain, but, for other periodic/aperiodic time-varying gains, they do. Overall, even when specialized to periodic-coefficient linear and nonlinear MIMO systems, the stability conditions are distinct from and less restrictive than recent results in the literature. No comparable results exist in the literature for aperiodic time-varying gains. Furthermore, some new stability results concerning the dwell-time problem and time-varying gain switching in linear and nonlinear MIMO systems with periodic/aperiodic matrix gains are also presented. Examples are given to illustrate a few of the stability theorems.

关键词： Circle criterion K-P-y lemma L2-stability Lur'e problem Multiplier function Nyquist's criterion Switched systems time-varying system

Finite Element Analysis of Push-Out test of SiC Fiber Reinforced titanium Matrix Composites

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稀有金属材料与工程 2009年第A03期38卷 50-53页

作者： yuan M N yang y Q huang B Zhang R J School of Materials Northwestern Polytechnical University Xi＇an 710072 China

Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of titanium matrix composites(tMCs) and to analyze the effects of various parameters on the interfacial properties. the results showed that the improved interface model is more suitable for calculating the interfacial properties of SiC fiber reinforced titanium matrix composites. the interfacial shear strength of SiC/timetal-834 predicted is 500 MPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.

关键词：复合材料剪切强度碳化硅纤维物理性能