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large Scale Perturbations in Extratropical Atmosphere-Part Ⅱ: On Geostrophic Waves

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Advances in Atmospheric Sciences 1993年第2期10卷 181-192页

作者： y.l. McHall Department of Earth Atmospheric and Planetary Sciences MIT MA 02139 USA

We have examined, in Part Ⅰ, the propagation mechanism and geostrophic property of classical Rossby waves in a non-divergent barotropic atmosphere. As we found that the non-divergent Rossby waves do not propagate in a hydrostatically equilibrium atmosphere, and do not manifest a good geostrophic property, an alternative large scale circulation pattern of geostrophic waves has been proposed (McHall, 1991a). The propagation mechanism and geostrophic property of these waves are examined in the present study.

关键词： On Geostrophic Waves large Scale Perturbations in Extratropical Atmosphere-Part

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

河北坝上杨树人工林径向生长与气候因子关系数据集

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全球变化数据学报（中英文） 2022年第1期6卷 65-72,I0067-I0074页

作者：刘亚玲信忠保李宗善买尔当·克依木北京林业大学水土保持学院北京100083 中国科学院生态环境研究中心北京100085

作者在河北省坝上地区波罗素林场(41°03’N-41°27’N,114°20’E-115°58’E)采集了健康和衰退杨树树芯样品,进行实验分析后得到河北坝上地区杨树径向生长与气候因子关系数据集。该数据集包括:(1)河北坝上小叶杨防护林样地基本信息;(2... 详细信息

作者在河北省坝上地区波罗素林场(41°03’N-41°27’N,114°20’E-115°58’E)采集了健康和衰退杨树树芯样品,进行实验分析后得到河北坝上地区杨树径向生长与气候因子关系数据集。该数据集包括:(1)河北坝上小叶杨防护林样地基本信息;(2)健康和衰退杨树标准年表及年表主要特征参数和公共区间分析结果;(3)健康和衰退杨树生长与气候因子关系分析数据,即,健康和衰退杨树年表与单月和季节尺度气候因子的相关性(月平均温度、月最高温度、月最低温度、月降水量、月平均相对湿度、帕默尔干旱指数)以及健康和衰退杨树年表与主要月份气候因子的滑动相关分析(月平均温度、月最高温度、月降水量、帕默尔干旱指数);(4)健康和衰退小叶杨树轮宽度时间序列及交叉定年检验结果。数据集存储为.txt、.xlsx、.out格式,由4个数据文件组成,数据量为404 KB(压缩为1个文件,152 KB)。

关键词：河北坝上小叶杨衰退径向生长气候响应

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

low-cost and fluoride-free synthesis of MFI zeolite nanosheets with enhanced stability for benzene alkylation with ethanol

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Journal of Energy Chemistry 2025年第1期100卷 458-468页

作者： Peng Zhu Cun liu yiren yu Guoshu Gao yumeng Zhao Xiongfu Zhang Guodong liu Guohui yang State Key.l.boratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology State Key.l.boratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences

Zeolite nanosheets with a short b-axis thickness are highly desirable in lots of catalytic reactions due to their reduced diffusion resistance. Nevertheless, conventional synthesis methods usually require expensive structure-directing agents(SDAs), pricey raw materials, and eco-unfriendly fluorine-containing additives. Here, we contributed a cost-effective and fluoride-free synthesis method for synthesizing high-quality MFI zeolite nanosheets through a Silicalite-1(Sil-1) seed suspension and urea cooperative strategy, only with inexpensive colloidal silica as the Si source. Our approach was effective for synthesizing both Sil-1 and aluminum-containing ZSM-5 nanosheets. By optimizing key synthesis parameters,including seed aging time, seed quantity, and urea concentration, we achieved precise control over the crystal face aspect ratio and b-axis thickness. We also revealed a non-classical oriented nanosheet growth mechanism, where Sil-1 seeds induced the formation of quasi-ordered precursor particles, and the(010)crystal planes of these particles facilitated urea adsorption, thereby promoting c-axis-oriented *** obtained ZSM-5 nanosheets exhibited exceptional catalytic performance in the benzene alkylation with ethanol, maintaining stability for over 500 h, which is 5 times longer than traditional ZSM-5 catalysts. Furthermore, large-scale production of ZSM-5 nanosheets was successfully carried out in a 3 l highpressure autoclave, yielding samples consistent with those from laboratory-scale synthesis. This work marks a significant step forward in the sustainable and efficient production of MFI nanosheets using inexpensive and environmentally friendly raw materials, offering the broad applicability in catalysis.

关键词： Aspect ratio

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