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3T MR多参数成像对前列腺癌检测价值与病理组织学对照研究

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国际医学放射学杂志 2010年第3期 280-280页

作者：孙美玉 B. Turkbey P.A. Pinto H. Mani M. Bernardo y.l. mckinney Molecular Imaging Program National Cancer Institute National Institutes of Health

摘要目的探讨以全标本前列腺病理检查结果为标准时,3T多参数MR成像方法(T2加权成像、MR波谱和动态对比增强MR成像)检

关键词：前列腺癌动态对比增强波谱多参数成像 MR 对照研究

A NOVEl METHOD FOR EVAlUATING PlANE STRESS DyNAMIC FRACTURE TOUGHNESS OF 0Cr18Ni10Ti STAINlESS STEEl WElDED JOINTS

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Acta Metallurgica Sinica(English letters) 2008年第4期21卷 303-312页

作者： Z.J. Xu y.l. li School of Aeronautics Northwestern Polytechnical University Xi＇an 710072 China

A novel method was proposed for the evaluation of Mode I dynamic fracture toughness （DFT） under plane stress and small scale yielding conditions for welded joints of stainless steel （SS）, 0Cr18Ni10Ti. In a hybrid experimental-numerical approach, the experiments were carried out on the Hopkinson pressure bar apparatus, and three dimensional （3D） transient numerical simulations were performed by a finite element （FE） computer program. Macroscopical plastic deformation was observed at the loading and supporting points, on the specimens, after the test, which could cause a large error if omitted in the numerical simulation. Therefore, elustic-viscoplustic analysis was performed on the specimen by adopting the Johnson-Cook （J-C） model to describe the rate-dependent plastic flow behavior of the material. The material heterogeneity in the mismatched welded joints, induced by the difference in the base metal （BM） and the weld metal （WM） in yield stress, has also been taken into consideration by using the J-C models separately. Good accordance was obtained between the experimental and the computational results by the present approach. The relationship between plane stress DFT and loading rate was also obtained on the order of 108 MPa.m^1/2.s^-1.

关键词： 0Cr18Ni10Ti Welded joint High strain rate Dynamic fracture Plane stress

EFFECT OF QUENCHING TEMPERATURE ON SHAPE MEMORy EFFECT OF Fe-18Mn -5Si-8Cr-4Ni AllOy

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Acta Metallurgica Sinica(English letters) 1999年第5期12卷 739-742页

作者： Wen, y.H. li, N. Xu, y.G. Tu, M.J. li, y.l. Ma, y.l. Sichuan Univ Chengdu China

The effects of quenching temperature on shape memory effect and microstructure of Fe 18Mn 5Si 8Cr 4Ni shape memory alloy have been studied. The results show that both the shape recovery ratio and the recovery strain increased as quenching temperature increased, the amount of stress induced ε martensite in the process of cold work decreased with the increase of quenching temperature, the shape recovery ratio and the recovery strain reached maximum at 650℃, and then decreased rapidly with the further increase of quenching temperature,the stress induced ε martensite wholly disappeared at 1023K. But when the quenching temperature is higher than 1023K, the further increase of quenching temperature had little effect on shape recovery ratio, the amount and size of thermal induced ε martensite would increased with the further increase in quenching temperature. The shape memory effect can be improved by the moderate amount of pre exist ε martensite in the matrix before deforming.

关键词： shape memory alloy shape recovery ratio ,martensite transformation

STUDy ON VERTICAl WATER TEMPERATURE MODEl FOR MIyUN RESERVOIR

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Journal of Hydrodynamics 2000年第4期12卷 75-83页

作者： li, y.l. Chen, y.C. Zhang, B.X. Dep. of Hydraulic Eng. Tsinghua Univ. Beijing 100084 China

According to the characters of the Miyun reservoir located in northeast Beijing, one-dimensional method is used to establish a mathematical model of temperature for the reservoir. In this model the heat exchange between water surface and atmosphere, effective diffusion, inflows, outflows, and thermal advection are considered comprehensively. The effective diffusion coefficient, decay coefficient of short wave in water, etc, are calibrated based on the observed stratification data of 1991 in the reservoir. The mathematical model is verified through the agreement with the data of 1992. This model can be used to predict the temperature distribution along the vertical direction for the Miyun reservoir and other similar reservoir.

关键词： Computer simulation Heat transfer Mathematical models Temperature distribution

EFFECT OF HEAT TREATMENT ON RECOVERy STRESS OF Fe-18Mn-5Si-8Cr-4Ni AllOy

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Acta Metallurgica Sinica(English letters) 1999年第5期12卷 743-746页

作者： li, N. Wen, y.H. Xu, y.G. Tu, M.J. li, P.Q. liu, y.l. Ma, y.l. Sichuan Univ Chengdu China

The effect of quenching temperature on the recovery stress of Fe 18Mn 5Si 8Cr 4Ni shape memory alloy has been studied. The results show that both the maximum recovery stress σ h in heating and the recovery stress σ c at room temperature after heating increased as increasing quenching temperature increased, both σ h and σ c reached maximum at 650℃, and then decreased rapidly with the further increase in quenching temperature,but the descent degree of σ c was far bigger than that of σ h; When the quenching temperature is higher than 850℃, the further increase in quenching temperature had little effect on them; At random quenching temperature, σ c was far bigger than σ h.

关键词： shape memory alloy quenching recovery stress

DIFFERENCE SCHEMES WITH NONUNIFORM MESHES FOR NONlINEAR PARABOlIC SySTEM

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Journal of Computational Mathematics 1996年第4期14卷 319-335页

作者： y.l. Zhou(laboratory of Computational Physics, Centre for Nonlinear Studies, Institute of AppliedPhysics and Computational Mathematics, Beijing, China) INST APPl PHyS & COMPUTAT MATH CTR NONLINEAR STUDIESLAB COMPUTAT PHYSBEIJING 100088PEOPLES R CHINA

The boundary value problem for the nonlinear parabolic system is solved by the finite difference method with nonuniform meshes. The existence and a priori estemates of the discrete vector solutions for the general difference schemes with unequal meshsteps are established by the fixed point technique. The absolute and relative convergence of the discrete vector solution are justified by a series of a priori estimates. The analysis of mentioned problems are based on the assumption of heuristic character concerning the existence of the unique smooth solution for the original problem of the nonlinear parabolic system.

关键词： Math QT DIFFERENCE SCHEMES WITH NONUNIFORM MESHES FOR NONlINEAR PARABOlIC SySTEM

Template-free Fabrication and luminescent Characterization of Highly Uniform and Monodisperse y_2O_2S:Sm^(3+) Hollow Submicrospheres

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Journal of Materials Science & Technology 2012年第7期28卷 666-672页

作者： S.Q. Deng Z.P. Xue y.H. yang Q. yang y.l. liu Department of Chemistry Jinan University Guangzhou 510632 China

Well dispersed and homogeneous y2O2S：Sm3＋ hollow submicrospheres were successfully achieved by a template- free solvothermal method combining with a postcalcining process. The crystalstructure and particle morphology were investigated by the X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, scanning and transmission electron microscopy （SEM and TEM）, respectively. A possible growth mechanism was proposed to reveal the formation process. luminescence properties of the y202S：Sm3＋ long-lasting phosphor were an- alyzed by measuring the excitation spectra, emission spectra, afterglow decay curve and thermoluminescence curve. The excitation spectra indicated that the phosphor could be excited effectively by the ultraviolet-light emitting diode （UV-lED） or blue lED, and the emission spectra showed that the phosphor could emit red light from 600 to 650 nm.

关键词： yttrium oxysulfide Hollow submicrosphere luminescence long-lasting phosphor

STUDy ON REDUCING THE CORE lOSS OF GRAIN ORIENTED SIlICON STEEl AND IMPROVING ITS AGING PROPERTy By.l.SER NITRIDING TECHNIQUE IN ATMOSPHERIC AMBIENT

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Acta Metallurgica Sinica(English letters) 2005年第4期18卷 533-538页

作者： y.l. yang C.S. liu F.J. Sun D. Zhang College of Science Northeastern University Shenyang 110004 China College of Material ＆ Metallurgy Northeastern University Shenyang 110004China

CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.

关键词： laser nitriding grain oriented silicon steel sheet core loss aging property

IMPROVING THE SURFACE PROPERTy OF TC4 AllOy By.l.SER NITRIDING AND ITS MECHANISM

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Acta Metallurgica Sinica(English letters) 2006年第2期19卷 151-156页

作者： y.l. yang G.J. Zhao D. Zhang C.S. liu Gollege of Sdence Northeastern University Shenyang 110004 Ghina College of Material and Metallurgy Northeastern University Shenya g 110004 China

The mixing technology of laser and heated nitrogen was applied to improve the surface hardness of titanium alloy （ TC4 ）. The samples were nitrided with laser power density of 6.S × 10^6SW. cm^-2, the scanning speed varioas from 100 to 500mm ·min^-1. The nitrogen gas was pre-heated to 300℃ to accelerate the nitriding process. Some interested samples were tested with XRD method （X-ray diffraction） to analyze the composition of nitrides, and the surface hardness of HV was measured. The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which is from the original value of 269to 794kg·mm^-2. The mechanism of the mixing technology is considered mainly of the activation of nitrogen by.l.ser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors： the first reason is the result of laser annealing, and the second one is the formation of TiN.

关键词： laser nitridation surface property Ti alloy