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3D FINITE ELEMENT ANALYSIS OF THE DAMAGE EFFEcTS ON THE DENTAL cOMpOSITE SUBJEcT TO WATER SORpTION

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Acta Mechanica Solida Sinica 2006年第3期19卷 212-222页

作者： Tsui c.p. chow c.L. Department of Industrial and Systems Engineering The Hong Kong polytechnic University Hong Kong ChinaDepartment of Mechanical EngineeringThe University of Michigan-DearbornDearbornMichiganUSA

The damage effects of water sorption on the mechanical properties of the hydroxyapatite particle reinforced Bis-GMA/TEGDMA c.p.lymer （HA/Bis-GMA/TEGDMA） h-ave been predicted using 3D finite cell models. The plasticizer effect on the polymer matrix was considered as a variation of its Young＇s modulus. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode clarified. The Young＇s modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. ine Iormer results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The Fcc cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.

关键词： water sorption dental composite interphase debonding finite element method (FEM) unit cell model

pREDIcTION FOR FORMING LIMIT OF AL2024T3 SHEET BASED ON DAMAGE THEORY USING FINITE ELEMENT METHOD

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Acta Mechanica Solida Sinica 2006年第2期19卷 174-180页

作者： Tang c.Y. Fan Jianping Tsui c.p. Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China School of civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China

This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microsc.p.c damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study.

关键词： forming limit diagram (FLD) anisotropic damage finite element method (FEM) limit strain localized necking elasto-plastic deformation

cOMpUTATION OF FLEXURAL pROpERTIES OF HA/pLLA cOMpOSITE USING A cELL MODEL AppROAcH

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Acta Mechanica Solida Sinica 2006年第1期19卷 18-25页

作者： Fan Jianping Tang chak-Yin Tsui c.p. School of civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China

A three-dimensional finite element analysis was conducted to evaluate the feasibility of predicting the flexural properties of hydroxyapatite-reinforced poly-L-lactide acid （HA/pLLA） biocomposite using three different schemes. The scheme 1, originated from a beam analysis, was used to determine the flexural modulus analytically while the scheme 2 and 3 were designed to have different loading and boundary conditions using a finite element cell modeling approach. An empirical approach using chow＇s formula and experimental data were used for comparison with the predicted results. In order to reduce the computational time and save the storage space involved in determining the effect of varying particle volume fractions on the flexural properties of HA/pLLA, a superelement technique was applied. The results using the scheme 3 and the chow＇s formula were found to be in reasonable agreement with experimental results over the range of particle volume fraction. In addition to the chow＇s formula, local stress distribution and the failure processes in HA/pLLA were simulated using the finite element technique.

关键词： composite hydroxyapatite (HA) poly-L-lactide acid (pLLA) finite element method(FEM) cell model flexural properties particle volume fraction (pVF)

A mathematical solution for the parameters of three interfering resonances

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chinese physics c 2018年第4期42卷 62-68页

作者： X. Han c.p. Shen School of physics and Nuclear Energy Engineering Beihang University Beijing 100191 China

The multiple-solution problem in determining the parameters of three interfering resonances from a fit to an experimentally measured distribution is considered from a mathematical viewpoint. It is shown that there are four numerical solutions for a fit with three coherent Breit-Wigner functions. Although explicit analytical formulae cannot be derived in this case, we provide some constraint equations between the four solutions. For the cases of nonrelativistic and relativistic Breit-Wigner forms of amplitude functions, a numerical method is provided to derive the other solutions from that already obtained, based on the obtained constraint equations. In real experimental measurements with more complicated amplitude forms similar to Breit-Wigner functions, the same method can be deduced and performed to get numerical solutions. The good agreement between the solutions found using this mathematical method and those directly from the fit verifies the correctness of the constraint equations and mathematical methodology used.

关键词： multiple solutions three interfering resonances high energy physics experiments

Molecular cloning of rice cDNAs related to pollen development using the subtraction hybridization technique

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chinese Science Bulletin 1999年第20期44卷 1898-1903页

作者： Zee S.Y Yau c.p. The Botany Department University of Hong Kong Hong Kong ChinaThe Botany Department University of Hong Kong Hong Kong China

The meiotic stage of pollen mother cell is a very important stage in controlling the development and formation of pollen. In order to clone the rice cDNA(s) of this stage, a normal rice, Annong N and its thermosensitive mutant, Annong S-1 were used as the plant material. The mRNA has been extracted from the young panicle at the meiotic stage. By using the cDNA subtraction hybridization technique, three cDNA fragments, Rp-1, Rp-2 and Rp-3 have

关键词： cDNA subtraction hybridization pollen development rice.

Hot cracking in AZ31 and AZ61 Magnesium Alloy

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Journal of Materials Science & Technology 2011年第7期27卷 633-640页

作者： c.J. Huang c.M. cheng c.p. chou F.H. chen Department of Mechanical Engineering National Chiao Tung University Hsinchu 300 Taiwan China Department of Industrial Education National Taiwan Normal University Taipei 106 Taiwan China

This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microsc.p. （SEM）, an energy dispersive spectrometer （EDS） was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susc.p.ibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone （pMZ）. In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher （6 wt%） Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susc.p.ibility was lower than AZ61. In addition, AZ61 showed longer total crack length （TcL） in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susc.p.ibility.

关键词： Varestraint test Thermal cycles Hot-cracking susc.p.ibility Gas tungsten arc welding (GTAW) AZ31 AZ61

Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary,West Himalaya

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Journal of Mountain Science 2018年第9期15卷 1936-1949页

作者： cHANDRA Sudeep SINGH Ankit SINGH c.p. NAUTIYAL M.c. RAWAT L.S. High Altitude plant physiology Research centre(HAppRc)H.N.B.Garhwal University Srinagar Garhwal-246174UttarakhandIndia Space Applications centre (Indian Space Research Organization)Ahmedabad 380015India Govind Ballabh pant National Institute of Himalayan Environment&Sustainable Development Garhwal Unit Srinagar Garhwal-246174UttarakhandIndia

The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient and sampled for detailed vegetation analysis using multi summit approach as per Global observation research initiative in alpine environments(GLORIA). Species richness, diversity, and evenness among four summits as well as the interaction between environmental variables with plant communities were assessed. Monthly mean soil temperature was calculated using data retrieved from geo-precision temperature logger in order to identify the trend of soil temperature among different season and altitudinal gradient and its implications to plant communities. Soil samples were analyzed fromeach summit by collecting randomized composite soil samples. The indirect non-metric multidimensional scaling(NMDS) and direct canonical correspondence analysis(ccA) tools of ordination techniques to determine the linkage between plant species from various sample summits and biotic/abiotic environmental gradients were used in the present study. The results of the study demonstrated increase in species richness as soil temperature increases, the ecotone representing summits were found most warm summits followed by highest species richness. Annual soil temperature increased by 1.43°c at timberline ecotone. Whereas, at upper alpine zone the soil temperature increased by 0.810 c from year 2015 to 2016. S?rensen's similarity index was found to be increased between subalpine and upper alpine zone with increase in the presence of subalpine plant species at upper alpine zone. Both the ordination tools separate the subalpine summit and their respective vegetation from summits representingtimberline ecotone and upper alpine zone. Soil p H, altitude, soil cation exchange c.p.city were found as the key abiotic drivers for distribution of plant species.

关键词： GLORIA Non-metric multidimensionalscaling (NMDS) canonical correspondence analysis(ccA) Ecotone West Himalaya

Tort law :responsibilities and redress 2nd ed.

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A High power conversion Efficiency L-Band Erbium Doped Fiber Amplifier

2008年

作者： John c.p. Goldberg Anthony J. Sebok Benjamin c. Zipursky

来源：畅想之星图书光盘版（南... 评论

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畅想之星图书光盘版（南通市图书馆镜像）

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光学学报 2003年第S1期23卷 383-384页

作者： Z.G. Lu c.p. Grover Institute for National Measurement Standards National Research Council M-50 1200 Montreal Road Ottawa ON K1 A OR6 CanadaInstitute for National Measurement Standards National Research Council M-50 1200 Montreal Road Ottawa ON K1 A OR6 Canada

By using two sections of erbium doped fiber and a fiber optical reflector, a novel, highly efficient L-band amplifier is demonstrated with significantly power-conversion-efficiency enhancement and the gain increasing ... 详细信息

关键词： EDFA as of length high with A High power conversion Efficiency L-Band Erbium Doped Fiber Amplifier ASE been for