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VISCOUS-INVISCID INTERACTING FLOW THEORY

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Acta Mechanica sinica 1990年第2期6卷 102-110页

作者： Gao Zhi (institute of Mechanics,academia sinica) institute of Mechanics Academia Sinica Beijüng China

In this paper a viscous-inviscid interacting flow theory(IFT)is developed for an incompressible, two-dimensional laminar ***'s main points are as follows.(1)By introducing a concept of interaction lay- er where the normal momentum exchange is dominating,a new three layer structure is established.(2)Through the conventional manipulations and by introducing an interaction model,both the streamwise and normal length scales are proved to be functions of a single parameter m,which is related to the streamwise pressure gradient and Reynolds number.(3)The approximate equations governing the flow of each layer as well as the whole interaction flow are *** present IFT is applicable to both attached and attached-separation bubble-reattached flows, The classical boundary layer theory and Triple-deck theory are shown to be two special cases of the present theory under m=0 and 1/4,*** IFT provides new distinctions of both the normal and streamwise length scales for flow-field numerical computation and also gives a new approach to developing the simpli- fied Navier-Stokes(SNS)equations.

关键词： fluid mechanics viscous flow separation flow boundary layer flow

Morphology of Branch Chain in Copolymer Surfactants on Interface

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Chinese Chemical Letters 1996年第10期7卷 948-950页

作者： Jian XU Liang He SHI Mei Ling YE(Polymer Physics laboratory,institute of Chemistry, academia sinica, Beijing 100080) Polymer Physics laboratory Institute of Chemistry Academia Sinica Beijing 100080

The conformation of amphiphilic branch chain in acrylamide-poly(oxyethylene alkyl ether) acrylate copolymers on interface was investigated by static laser light scattering amid X-ray photoelectron spectroscopy. The re...

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DEVELOPMENT OF HOLOCENE CORAL REEFS IN CHINA AND THEIR REFLECTION ON SEA LEVEL CHANGES AND TECTONIC MOVEMENT

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Science in China,Ser.B 1983年第4期26卷 413-423页

作者：赵希涛 institute of geology academia sinica Beijing

In this paper the provinces and characteristics of coral reefs in China are described, the formative ages of the Holocene coral reefs and their reflection on sea level changes are discussed, and the rates of vertical ... 详细信息

关键词： DEVELOPMENT OF HOLOCENE CORAL REEFS IN CHINA AND THEIR REFLECTION ON SEA LEVEL CHANGES AND TECTONIC MOVEMENT CBML In NTU

PREPARATION,PROPERTIES AND INTERFACE STRUCTURES OF Si_3N_(4w)/6061Al COMPOSITE

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Acta Metallurgica sinica(English Letters) 1992年第11期5卷 423-428页

作者： PAN Jin Changsha institute of Technology,Changsha,ChinaNING Xiaoguang YE Hengqiang laboratory of Atomic Imaging of Solids,institute of Metal Research,academia sinica,Shenyang,China Changsha Inst of Technology Changsha China

The Si_3N_4 whisker reinforced 6061Al composite with bending strength of 790 MPa was prepared by squeeze casting *** heat-treatment under T6 regime i.e.530℃, 1 h solutioning and 160℃,24 h aging,an increment in strength and microhardness may be over 20% and 28% respectively,The microstructures of Si_3N_4 whisker and Si_3N_4/Al interface were observed by meas of *** relation between interracial structure and composite properties was discussed.

关键词： β-Si_3N_4 wthisker Al matrix composite strength interface

HYDROGEN PERMEATION AND DIFFUSION IN ALLOY INCOLOY 903

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Acta Metallurgica sinica(English Letters) 1993年第3期6卷 163-167页

作者： XU Jian SUN Xiukui CHEN Wenxiu LI Yiyi State Key laboratory of RSA,institute of Metal Research,academia sinica,China research assistant,institute of Metal Research,academia sinica,Shenyang 110015,China Inst of Metal Research Acad Sinica Shenyang China

Permeability and diffusivity of hydrogen in Fe-Ni-Co based superalloy lncoloy 903 were measured over the temperature range of 220 to 420℃ using a gaseous permeation technique. The effect of strengthening phase γ' precipitated after being aged on the hydrogen permeation and diffusion was *** was indicated that the permeability and diffusivity of hydrogen in the alloy hardly depend on heat treatment condition and are not af- fected by γ' phase precipitated after being *** relationships between the permeability and diffusivity of hydrogen and the temperature can be respectively expressed as Φ=9.36×10^(-5)exp[-54.20(kJ/mol)/RT]mol/m·s·MPa^(1/2)and D=4.24×10^(-7)exp[-49.07(kJ/mol)/RT]m^2/s.

关键词： hydrogen permeation hydrogen diffusion superalloy precipitation phase Incoloy 903

Ordovician-Silurian Boundary Extinction and Its Relationship to Iridium and carbon Isotope Anomalies

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Acta Geologica sinica(English Edition) 1990年第1期64卷 81-92页

作者： Wang Xiaofeng Chai Zhifang Yichang institute of geology and Minieral Resources, Chinese Academy of Geological Sciences, Yichang. Hubei institute of High Energy, academia sinica, Beijing Liu Linqun Yichang institute of geology and Mineral Resources Chinese Academy of Geological Sciences Yichang Hubei China

The abundance distributions of more than 40 elements in the No. 502 Ordovician-Silurian (O/S) bounda-ry section at Fenxiang, Yichang have been studied by RNAA and INAA. The results show that in the bounda-ry bed, there is a distinctive Ir anomaly because the Ir concentration abruptly increases to 0.64 ppb.Furthermore, the Ir is positively correlated in abundance variation with some siderophile and sulphophile ele-ments. In the same bed of the O/S boundary section at Huanghuachang, Yichang, there is also a δ^(13)C excur-sion. These geochemical signs support the hypothesis that the terminal Ordovician mass extinction was proba-bly related to extraterrestrial event, and provide new evidence for defining the O/S boundary between theHirnantia-Kinnella and G. persculptus Zones.

关键词： Ordovician-Silurian Boundary Extinction and Its Relationship to Iridium and carbon Isotope Anomalies Chen Wang

Characteristics and Formation Mechanism of the Geothermal Field in the North China Downfaulted Basin

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Acta Geologica sinica(English Edition) 1990年第3期64卷 329-343页

作者： Chen Moxiang Wang Jiyang Wang Ji’an Deng Xiao Yang Shuzhen Xiong Liangping Zhang Juming institute of geology, academia sinica, Beijing Liu Linqun institute of geology Academia Sinica Beijing

The geothermal field is mainly controlled by the regional tectonic framework characterized by alternationsof uplifted and depressed basement. and exhibits a similar zoned distribution of temperatures. In the upliftedarea the geothermal gradient （G） and terrestrial heat flow value（q） of the Cenozoic sedimentary cover are rela-tively high, with G=3.5-5.0℃/100m and q=63-84mW/m;; whereas in the depressions they are rela-tively low, with G=2.7-3.5℃/100m and q=46-59mW/m;. In the whole region, G=3.58℃/100m and q=61.5±13.4nW/m;, indicating a comparatively high geothermal background and the presence of localgeothermal anomalies. A comparison of the results of mathematical simulation of the geothermal field with themeasured values shows a good agrecment between them. The geothermal difference between various tectonicunits is caused chiefly by the lateral and vertical variation of thermal properties of shallow crustal rocks. Thisphenomenon can be regarded as the result of redistribution of relatively uniform heat flows from the deep crustin the surficial part of the crust in the process of their upward conduction.

关键词： Characteristics and Formation Mechanism of the Geothermal Field in the North China Downfaulted Basin

NONLINEAR STABILITY AND BIFURCATIONS OF SYMMETRIC HEAVY GYROSCOPE

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Acta Mechanica sinica 1990年第2期6卷 180-187页

作者： Zhu Ruzeng (institute of Mechanics,academia sinica) institute of Mechanics Academia Sinica Beijing China

The complete solutions of the upright and oblique permanent rotations of a symmetric heavy gyroscope with perfect dissipation are *** asymptotic stability criteria and unstability criteria for these rotations in the sense of Liapunov and the sense of Movchan are also given on the basis of exact nonlinear motion equations *** related oblique rotations are *** main subdomains of the re- gions of asymptotic stability are *** related bifurcation phenomena are discussed in detail.

关键词： heavy gyroscope nonlinear stability bifurcation dissipative force

On problem of the determination of operational mode of towed line array with distorted shape

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Chinese Journal of Acoustics 1990年第2期9卷 139-144页

作者： LI Qihu(institute of Acoustics, academia sinica)

The distortion of the array shape is one of the main factors which result the performance degeneration from the ideal situation of towed line array (TLA). Based on the ordinary array shape distortion, the directivity function of TLA is presented in this paper. An algorithm for precisely determning the coordinates of each element by means of the inverse elliptic function is derived. A fast approximation of recursive formula for solving distorted array shape is given. According to the comparison between ideal directivity and the directivity of distorted array, the criterion for making decision of operational mode of TLA sonar is presented. So that the performance prediction problem in TLA is solved. The results of system simulation in computer show a good agreement with the theoretical analysis.

关键词： TLA On problem of the determination of operational mode of towed line array with distorted shape line mode