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INFLUENCE OF INITIAL TEXTRUE ON THE COLD ROLliNG TEXTURE OF Ti SHEETS

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中国有色金属学会会刊：英文版 1995年第2期5卷 66-70页

作者： Mao, Weimin Yu, Yongning li, Botao(university of Science and Technology {2., 100083 {2.) Univ of Science and Technology Beijing Beijing China

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关键词： Ti Rolling Texture ODF

Discovery of Paleogene marine stratum along the southern side of Yarlung-Zangbo suture zone and its implications in tectonics

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Science China Earth Sciences 2005年第5期48卷 647-661页

作者： li Guobiao 1 , WAN Xiaoqiao 1 , liU Wencan 1 , liANG Dingyi 1 & Hyesu Yun 2.1. China university of Geosciences, beijing 100083, China 2. Chungnam National university, Daejon, 305-350, Korea 1. China university of Geosciences 100083 Beijing China 2. Chungnam National university 305-350 Daejon Korea

The Jiachala Formatiom is a new lithostratigraphic unit set up in this paper. This is the first report on the Paleogene marine sequences and microfaunas in Gyangze to the southern side of the Yarlung-Zangbo suture zone. On the basis of fossil abundance, species diversity, dominant species and first and last occurrences of key species, three dinoflagellate assemblages and three polynological assemblages were recognized in the Jiachala Formatiom. They are in ascending order as follows: Apectodinium quinquelatum-Apectodinium hyperacanthum, Cannin- gia chinensis-Palaeoperidinium pyrophorum and Cymatiosphaera reticulosa-Samlandia chla- mydophora dinoflagellate assemblages, and Arliaceoipollenites baculatus-Anacolosidites sub- trudens, Aglaoreidia cyclops-Pinuspollenites microinsigis, and Elaeangnacites asper-Ilexpol- lenites iliacus polynological Assemblages. According to the assemblages, the age of the Jiachala Formation is referred to Paleocene-early Eocene. The preliminary study on the Jiachala Forma- tion shows that this group of Paleogene deposits accumulated in an underfilled peripheral fore- land basin which was in response to the load of the crust thickening resulted from the Asia-India collision. The stratigraphic evidences provided by the evolution of foreland basin indicate that the India-Asia initional collision should occure near the Cretaceous/Paleogene boundary. The de- velopment and evolution of the southern Tibet foreland basin was under the control of the stress field from the subduct-collision between India and Asia and the structure pattern of the basement. The withering of Tethys Sea might occur after early Eocene in the Gyangze basin and should be after Priabonian of late Eocene in southern Tibet.

关键词： Paleogene marine strata, Jiachala Formation, microfossils, underfilled peripheral foreland basin, initional collision, Gyangze.

CONVERGENCE PROPERTIES OF A MODIFIED BFGSALGORITHM FOR MINIMIZATION WITHARMIJO-GOLDSTEIN STEPLENGTHS

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Journal of Computational Mathematics 1999年第6期17卷 645-652页

作者： Nai-yang Deng Zheng-feng li(Department of Mathematics, beijing Agricultural Engineering {2., beijing 100083,China) beijing Agr Engn Univ Dept Math Beijing 100083 Peoples R China

The line search strategy is crucial for an efficient unconstrained optimization algorithm. One of the reason why the Wolfe line searches is recommended lies in that it ensures positive definiteness of BFGS updates. When gradient information has to be obtained costly, the Armijo-Goldstein line searches may be preferred. To maintain positive difiniteness of BFGS updates based on the Armijo-Goldstein line searches, a slightly modified form of BFGS update is proposed by I.D. Coope and C.J. Price (Journal of Computational Mathematics, 13 (1995), 156-160), while its convergence properties is open up to now. This paper shows that the modified BFGS algorithm is globally and superlinearly convergent based on the Armijo-Goldstein line searches.

关键词： BFGS methods convergence superlinear convergence

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central China: Constraints from geochemistry and melt inclusions

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Science China Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU li1,2. SONG Shuguang3 & ZHOU Dingwu1 1. Key Laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern university, Xi’an 710069, Ch{2. 2. The Geological Lab Center, Ch{2. university of Geosciences (beijing), beijing 100083, Ch{2. 3. Key Laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, Peking university, beijing 100871, Ch{2. 1. Key Laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. The Geological Lab Center China University of Geosciences 100083 (Beijing)Beijing China 3. Key Laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The Songshugou dunite body, which occupies an area of about 2. km2. is the largest ultramafic massif in the eastern Qinling orogenic belt, Central China. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2.3, CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

NEW APPROACH TO THE liMITER FUNCTIONS

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Journal of Computational Mathematics 1999年第1期17卷 41-58页

作者： Jin li Ze-min Chen Zi-qiang Zhu(beijing {2. of Aeronautics and Astronautics, beijing 100083, China) beijing Univ Aeronaut & Astronaut Beijing 100083 Peoples R China

In this paper we discuss three topics on the designing of the limiter functions. (1) To guarantee the TVD property (2. To maintain enough artificial viscosity. (3) A method to form TVB limiter which can ensure second ... 详细信息

关键词： finite difference methods TVD schemes limiter function

A WT-STFT combining Algorithm

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 315-317页

作者： Xisheng li, Shaochun Wang (Information Engineering School, university of Science and Technology {2., beijing 100083, China) Information Engineering School University of Science and Technology Beijing Beijing 100083 China

A fast wavelet packet (WP) algorithm is presented, in which the wavelet transform (WT) and the short-time Fourier transform (STFT) are combined. As WT produces multiresolution of frequency and time, and STFT has a fas... 详细信息

关键词： signal processing, wavelet transform short-time Fourier transform Informatid

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： li Sha and MAO Weimin School of Materials Science and Engineering,university of Science and Technology {2.,{2. 100083,China School of Materials Science and Engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72.kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Equilibrium Precipitation of Niobium Carbonitride in Austenite

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 119-122页

作者： Fuming Wang Wenchao li(Applied Science School, {2. of Science and Technology beijing, beijing 100083, China) Applied Science School University of Science and Technology Beijing Beijing 100083 China

The equilibrium between niobium carbonitride and austenite has been studied. Experimentally, X-raydiffaction technique was adopted to verify that the precipitates have the same composition and structure. Theoretical-ly, Hillert and Staffansson's regular model about stoichimetric phase was used to describe the thermodynamic proper-ties of multi-component precipitate. Calculated results agree well with experimental values from literatures.

关键词： equilibrium niobium precipitate, austenite

Improvement of Boxcar Integrator and Its Application to Low Resistance Measurement of Inductive Load Coil

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 180-184页

作者： Xisheng li Shaochun Wang(Information Engineering School, university of Science and Technology {2., beijing 100083, China) Information Engineering School University of Science and Technology Beijing Beijing 100083 China

A boxcar integrator is described which is suitable for the low-repetition-rate signal processing. This boxcar integrator, named fixed-interval mode boxcar integrator, is able to reject harmonics other than the first harmonic component. It can also decrease the effective time constant In many situations, the antialiasing filter with narrow bandwidth will cause distortion of the input signal. The fixed-interval mode boxcar integrator with suitable gate width can achieve relative high performance without signal distortion because the bandwidth of its antialiasing filter can be wider than that in the fixed-Point boxcar integrator. ms boxcar integrator is used as majn part of signalprocessing circult in the low resisance measurement of inductive load coil. The results of experiments show that the fixed-interval boxcar integrator is suitable for low-repetition-rate use.

关键词： signal processing resistance measurement boxcar integrator