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Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

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Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 183-189页

作者： Shan-tung TU Key Laboratory of Safety Science of Pressurized System Ministry of EducationEast China University of Science and Technology

The creep behavior of the plasma sprayed NiCr and NiCrA1 coating/Nickel alloy 690 substrate systems at 1033 K was investigated. results showed that there was almost no difference in the creep lives between the NiCr and NiCrA1 coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrA1 powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton＇s power law, εmin=Aσ^n, with the values of A=2.66×10^-16 MPa^-n·h^-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

关键词： Creep Coating θ projection method Minimum creep strainrate

Creep crack growth in a Cr-Mo-V type steel: experimental observation and prediction

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Acta Metallurgica Sinica(English Letters) 2011年第2期24卷 81-91页

作者： Shan-tung TU Key Laboratory of Safety Science of Pressurized System Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology

In this study, the creep crack growth （CCG） properties and fracture mechanism of a Cr-Mo-V steel at 566 C in compact tension （CT） specimens were investigated, and the CCG rate was predicted by using the NSW model. The results show that the CCG rate measured by CT specimens is much lower than that predicted by the NSW model under plane-strain state. This means that the NSW model prediction for the CCG rate of the steel is over-conservative. In addition, the CCG rate da/dt versus C measured by the experiments shows the piecewise linear relation on log-log scale instead of a single linear relation predicted by the NSW model. The main reasons for these results are that the actual creep fracture mechanism of the steel and the actual creep crack tip stress field in the CT specimens have not been fully captured in the NSW model. The experimental observation shows that the creep crack propagates in a discontinuous way （step by step） at meso-scale, and the cracks at micro-scale are usually formed by the growth and coalescence of voids on grain boundaries. The NSW model based on the creep ductility exhaustion approach may not correctly describe this creep fracture process. In addition, the opening stress and triaxial stress ahead of crack tips calculated by three-dimensional finite element method is lower than those predicted by the Hrr stress field which is used in the NSW model under plane-strain state. The use of the high Hrr stress field will cause high CCG rates. The change in the creep fracture mechanism at micro-scale in different ranges of C may cause the piecewise linear relation between the da/dt and C . Therefore, it is necessary to study the actual CCG mechanism in a wide range of C and the actual creep crack tip stress field to establish accurate CCG prediction models.

关键词： Creep crack growth Prediction NSW model Fracture mechanism Finite element method

Colorimetric and electrochemical Pb^(2+) detection by imine-bridged tetrathiafulvalene-pyridine derivatives

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Science China Chemistry 2009年第6期52卷 765-770页

作者： tung ChenHo Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry & Graduate University Chinese Academy of Sciences

Imine-bridged TTF-π-pyridine derivatives, 2NTTF, 3NTTF and 4NTTF, were synthesized and the cation-binding study was performed. It is noted that with the addition of the micromolar concentration of Pb2+ to the solution, these compounds display remarkable changes in solution color, 1H NMr spectra and electrochemical properties. The nitrogen atom of the imine-bridge in 2NTTF not only serves as a π-conjugated spacer but also participates in the sensing and coordinating properties.

关键词： tetrathiafulvalene intramolecular charge transfer imine-bridged TTF-π-pyridine derivatives Pb2+ recognition

小行星(554)Peraga的摄动和轨道的研究

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天文学报 1959年第2期 208-217页

作者：刘振銳童光裕胡坤林徐宗海中国科学院紫金山天文台佘山观象台

一、本工作的目的这顆小行星是哥茲(Gotz)于1905年在克尼斯杜耳(Konigstuhl)天文台发現的.历来沒有人研究过它的摄动。本工作的第一个目的是要利用小行星群普遍摄动的韓申-波林(Hansen-Bohlin)的原理,来研究它的摄动和軌道。这个行星的... 详细信息

一、本工作的目的这顆小行星是哥茲(Gotz)于1905年在克尼斯杜耳(Konigstuhl)天文台发現的.历来沒有人研究过它的摄动。本工作的第一个目的是要利用小行星群普遍摄动的韓申-波林(Hansen-Bohlin)的原理,来研究它的摄动和軌道。这个行星的平均周日运动是n=969″598,因此甚接近赫期吉亚(Hestia)和伏洛拉(Flora)两羣的边界(赫斯吉亚羣的范围是:825″rque)曾研究过行星(113)Amalthea的摄动,且得到的結果

关键词：摄动波林轨道根数 Peraga 行星长周期项

Complex geometry: Its brief history and its future

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Science China Mathematics 2005年第z1期48卷 47-60页

作者： Shing-tung Yau Department of Mathematics Harvard University CambridgeMA 02138USA

This paper reviews the brief history of complex geometry and looks into itsfuture.

关键词： complex geometry, complex manifold, Kahler manifold, Kahler-Einstein metric.

Geometric aspects of the moduli space of riemann surfaces

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Science China Mathematics 2005年第z1期48卷 97-122页

作者： Shing-tung Yau Department of Mathematics Harvard University CambridgeMA 02138USA

We describe some recent progress in the study of moduli space of riemann surfaces in this survey paper. New complete Kahler metrics were introduced on the moduli space and Teichmuller space. Their curvature properties and asymptotic behavior were studied in details. These natural metrics served as bridges to connect all the known canonical metrics, especially the Kahler-Einstein metric. We showed that all the known complete metrics on the moduli space are equivalent and have Poincare type growth. Furthermore,the Kahler-Einstein metric has strongly bounded geometry. This also implied that the logarithm cotangent bundle of the moduli space is stable in the sense of Mumford.

关键词： moduli space Teichmiiller space metric curvature.

A comprehensive consideration of bias voltage and temperature to extract the intrinsic frequency response of photodiodes

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Chinese Science Bulletin 2010年第32期55卷 3727-3733页

作者： tung ChenHo Chinese Academy of Sciences Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Frequency response is one of the most important characteristics of photodiode (PD). The upper limitation of the bandwidth of a PD is determined by its intrinsic frequency response. Based on the extraction method to extract the intrinsic frequency response,we take a further study to analyze the impact of the reverse bias voltage and the temperature on the frequency response of PDs. With the help of physical model,the experimental data and fitted results based on the reverse bias voltage and temperature separately are discussed,then the most reliable intrinsic frequency response of a PD is obtained.

关键词：固有频率响应光电二极管偏置电压提取方法温度国家环保总局物理模型实验数据

Supramolecular assemblies based on 2-ureido-4[1H]-pyrimidinone building block

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Chinese Science Bulletin 2006年第2期51卷 129-138页

作者： tung Chenho Technical Institute of Physics and Chemistry Chinese Academy of SciencesBeijing 100101 China

With high association constants in nonpolar solvents, the quadruple hydrogen bonding arrays of 2-ureido-4[1H]-pyrimidinones are recently considered to be one of the ideal building blocks to construct the complicated and functional supramole- cular systems. In this paper, we review the latest achievements of the supramolecular assemblies based on 2-ureido-4[1H]-pyrimidinone AADD quad- ruple hydrogen bonding building blocks.

关键词： 2-脲基-4[1H]-嘧啶酮超分子自组装氢键结合

Measurements of Non-reacting and reacting Flow Fields of a Liquid Swirl Flame Burner

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Chinese Journal of Mechanical Engineering 2015年第2期28卷 394-401页

作者： CHONG Cheng tung HOCHGrEB Simone Faculty of Mechanical Engineering Universiti Teknologi Malaysia Department of Engineering University of Cambridge

The understanding of the liquid fuel spray and flow field characteristics inside a combustor is crucial for designing a fuel efficient and low emission *** of the flow field of a model gas turbine liquid swirl burner is performed by using a2-D particle imaging velocimetry（PIV）*** flow field pattern of an axial flow burner with a fixed swirl intensity is compared under confined and unconfined conditions,i.e.,with and without the combustor *** effect of temperature on the main swirling air flow is investigated under open and non-reacting *** result shows that axial and radial velocities increase as a result of decreased flow density and increased flow *** flow field of the main swirling flow with liquid fuel spray injection is compared to non-spray swirling *** of liquid fuel spray changes the swirl air flow field at the burner outlet,where the radial velocity components increase for both open and confined *** reacting condition,the enclosure generates a corner recirculation zone that intensifies the strength of radial *** reverse flow and corner recirculation zone assists in stabilizing the flame by preheating the *** flow field data can be used as validation target for swirl combustion modelling.

关键词： flow field swirl flame gas turbine burner particle imaging velocimetry(PIV)