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PROPAGATION OF LONG-LIVED ANTICYCLONIC ROSSBY EDDIES OVER AN ISOLATED TOPOGRAPHY AND THEIR MERGING

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Journal of Hydrodynamics 2001年第3期13卷 34-45页

作者： Luo, De-Hai Lu, Yan Ocean univ. of Qingdao Qingdao 266003 China

In a barotropic model the propagation of long-lived anticyclonic Gaussian eddies larger than the radius of deformation over a Gaussian-shaped topography and the merging of the two anticyclonic eddies are investigated by solving the generalized Flierl-Yamagata equation. It is shown that whether or not the basic flow is present, the isolated topography seems to encourage the amplification of an anticyclonic eddy and its southwest movement around the hill In the absence of both the westward flow and the topography, two anticyclonic eddies of identical sizes and amplitudes can merge. However, either the including of the topography or the westward basic flow can make them not merge. In the presence of both, the eddies can merge, but this merging depends on whether the parameter condition is appropriate or not. Therefore, it can be concluded that the topographic forcing might be a possible mechanism for the merging of two anticyclonic eddies.

关键词： Amplification Equations of motion Merging Surface topography Two dimensional

Negotiating ＂Airy Curtains＂ Throughout the Cold War

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International Relations and Diplomacy 2014年第1期2卷 16-24页

作者： Christian Henrich-Franke univ.rsitat siegen Siegen Germany

This paper analyzes in a long-term perspective the evolution of the international system between the 1920s and the 1980s in the particular case of broadcasting frequency regulation. It addresses the constructing of ＂Airy Curtains＂--the immaterial equivalent to the Iron Curtain-along ideological frontiers by focusing on the International Telecommunication Union＇s frequency allocation conferences throughout the ＂Cold War＂. The question is raised： Which changes in the construction of ＂Airy Curtains＂ and the international system are observable in a long term perspective？ The paper answers this question by telling a story of specialization and differentiation of the international system. At the core of the paper the tensions between experts and diplomats in the negotiations on international regulations are discussed. The paper argues that in three periods the governance changed from an expert matter over a conflictual diplomatic period into a system where ＇Cold War engineers＇ and the ＇Engineering diplomats＇ took a pragmatic approach to the ideological conflicts and the political demand for Cold War broadcasting by a decoupling of politics and technology. In that context decision-making changed from ＂conference diplomacy＂ in the beginning to a complex process where many problems were solved outside the conferences themselves.

关键词： changing international relations expert governance cold war broadcasting

Microstructure and Mechanical Properties of TiB_2/(Ni+Mo) Composites Fabricated by Hot Pressing

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维普期刊数据库

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Journal of Materials Science & Technology 2000年第6期16卷 634-636页

作者： Zhang, J.Y. Fu, Z.Y. Wang, W.M. Wang, H. Wuhan univ. of Technol. Wuhan 430070 China

The fabrication of TiB2 ceramics with high performance at a relatively low temperature requires a second phase to assist the densification and control the microstructure. Moreover the interface characteristics of composites must also be considered. Nickel was chosen as a good metallic-bearing additive in this study. In order to optimize the interface, Mo was added. The results show that Mo can affect the interaction between TiB2 and Ni, and metallic liquid plays an important role in limiting the TiB2 grain growth in sintering.

关键词： NiMo Composites Fabricated by Hot Pressing Microstructure and Mechanical Properties of TiB2 Ni+Mo TiB

A LOOP DRAWBEAD RESTRAINING FORCE MODEL IN SHEET METAL DEEP DRAWING PROCESS

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Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 380-386页

作者： Y.J. Luo, S.P. Li, J.F. Zheng, D.N. He, Y.Q. Zhang, J.L. Cheng and J. Y. Jiang 1)National Mold & Die CAD Engineering Research Center, Shanghai 200030, China 2)Shanghai Volkswagen Automotive Company Ltd.(SVM), Shanghai 201805, China Shanghai Jiaotong univ. Shanghai 200030 China

In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.

关键词： drawbead restraining force sheet metal deep drawing

XPS Analysis of Ni and Oxygen in Single-Sintered SrTiO_3 Multifunction Ceramic

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Journal of Materials Science & Technology 2001年第5期17卷 535-537页

作者： Qing XU, Wen CHEN and Runzhang YUAN State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan univ.rsity of Technology, Wuhan 430070, China Wuhan univ. of Technol. Wuhan 430070 China

XPS analyses have been performed to investigate the chemical conditions of Ni and oxygen on grain surfaces in single-sintered SrTiO3 capacitor-varistor ceramic doped with Nb2O5 and NiO. It is ascertained that Ni is in form of Ni2+ ions, which substitute for Ti4+ ions on grain surfaces during the oxidizing annealing. Moreover, it is confirmed that three kinds of chemically adsorbed oxygen such as O2-, O- and O-2(-) are formed on grain surfaces. It is proposed that these behaviors contribute greatly to the generation of multiple types of grain boundary acceptor states in the ceramic.

关键词： XPS Analysis of Ni and Oxygen in Single-Sintered SrTiO3 Multifunction Ceramic Ni

Soil-structure interaction on shallow rigid circular foundation:plane SH waves from far-field earthquakes

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Earthquake Engineering and Engineering Vibration 2014年第1期13卷 29-45页

作者： Vincent W.Lee Hao Luo Civil & Environmental Engineering Univ. of Southern California HNTB Corporation

A closed-form wave function analytic solution of two-dimensional scattering and diffraction of incident plane SH-waves by a fl exible wall on a rigid shallow circular foundation embedded in an elastic half-space is presented. This research generalizes the previous solution by Trifunac in 1972, which tackled only the semi-circular foundation, to arbitrary shallow circular-arc foundation cases, and is thus comparatively more realistic. Ground surface displacement spectra at higher frequencies are also obtained. As an analytical series solution, the accuracy and error analysis of the numerical results are also discussed. It was observed from the results that the rise-to-span ratio of the foundation profi le, frequency of incident waves, and mass ratios of different media(foundation-structure-soil) are the three primary factors that may affect the surface ground motion amplitudes near the structure.

关键词： SH waves plane wave soil-structure interaction closed-form analytic solution Fourier-Bessel series

An On-line Monitoring System for Hydrogen Distribution in the Metallic Wall Caused by Hydrogen Permeation

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Journal of Materials Science & Technology 2001年第3期17卷 346-350页

作者： Gang YU Shenyang univ.rsity of Technology, 110023, China Xueyuan ZHANG and Yuanlong DU State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China E-mail: yugang@*** Shenyang univ. of Technol. Shenyang 110023 China

Based on the electrochemical permeation technique and the patent by Du, an intelligent elec-trochemical measurement system for determination of the hydrogen distribution in the wall of hydrogenation reactor has been developed and tested. It consists of a PC computer, a single chip unit, an I/V converter and an electrochemical hydrogen probe. The construction of the electrochemical hydrogen probe is described and the features of the measured system are given. The diffusion coefficient of 2.25CrlMo steel determined with present system was in good agree-ment with the value in the literature. Experimental results of hydrogen concentration in a wall of hydrogen charged testing autoclave made of AISI 321 stainless steel are presented. The present system can intelligently display hydrogen amount-of-substance concentration and mass fraction concentration, hydrogen concentration distribution curves in steels, permeation current density curve. An intelligent detection technique can be provided for predicting the susceptibility to hydrogen-induced cracks owing to hydrogen permeation in the wall of hydrogenation reactor in the field.

关键词： Hydrogen bonds

Fracture Behavior of Alumina-based Prismatic Ceramic Composites

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Journal of Materials Science & Technology 2001年第1期17卷 81-82页

作者： Guanghui MIN and Shuqi ZHENG Shandong univ.rsity of Technology, Jinan 250061, China T.Inoue and K. Ueno Osaka National Research institute, Ikeda City, Osaka 563, Japan Shandong univ. of Technol. Jinan 250061 China

The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.

关键词： Fracture Behavior of Alumina-based Prismatic Ceramic Composites

Fabrication of A1/Al_2O_3 Composites and FGM

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Journal of Materials Science & Technology 2001年第6期17卷 646-648页

作者： Hong TAO, Chengji DENG, Lianmeng ZHANG and Runzhang YUAN State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan univ.rsity of Technology, Wuhan 430070, China [Manuscript received November 27 Wuhan univ. of Technol. Wuhan 430070 China

Al/Al203 composites of different ratios were hot-press sintered at 575~640℃ under a pressure of 30 MPa for 2 h in a vacuum furnace. It was found that the relative density of the Al/Al203 composites could be increased evidently with the rise of sinter temperature. No reaction occurred between At and Al203 at the sinter temperatures. Under 640℃-30 MPa-2 h experimental condition, Al/Al203 system FGM was successfully fabricated, and its density range changed quasi-continuously from 2.887×103 kg/m3 to 3.1909×103 kg/m3 within the middle 1.0 mm thickness range.

关键词： Fabrication of Al/Al2O3 Composites and FGM Co Al