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Nonlinear Aeroelastic Response of High-aspect-ratio Flexible Wings

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Chinese Journal of Aeronautics 2009年第4期22卷 355-363页

作者： Zhang Jian,Xiang Jinwu School of Aeronautic Science and Engineering,beijing University of Aeronautics and Astronautics,beijing 100191,China School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

The aeroelastic analysis of high-altitude, long-endurance （HALE） aircraft that features high-aspect-ratio flexible wings needs take into account structural geometrical nonlinearities and dynamic stall. For a generic nonlinear aeroelastic system, besides the stability boundary, the characteristics of the limit-cycle oscillation （LCO） should also be accurately predicted. In order to conduct nonlinear aeroelastic analysis of high-aspect-ratio flexible wings, a first-order, state-space model is developed by combining a geometrically exact, nonlinear anisotropic beam model with nonlinear ONERA （Edlin） dynamic stall model. The present investigations focus on the initiation and sustaining mechanism of the LCO and the effects of flight speed and drag on aeroelastic behaviors. Numerical results indicate that structural geometrical nonlinearities could lead to the LCO without stall occurring. As flight speed increases, dynamic stall becomes dominant and the LCO increasingly complicated. Drag could be negligible for LCO type, but should be considered to exactly predict the onset speed of flutter or LCO of high-aspect-ratio flexible wings.

关键词： nonlinear aeroelasticity limit-cycle oscillation Galerkin methods geometrical nonlinearities dynamic stall HALEaircraft

局部-全局特征引导的图文多级关系分析与挖掘方法

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燕山大学学报 2024年第5期48卷 446-455页

作者：王海荣郭瑞萍徐玺周北京北方民族大学计算机科学与工程学院宁夏银川750021 北方民族大学图像图形智能处理国家民委重点实验室宁夏银川750021

具有语义相关性的文本、图像数据往往具有互补性,可以从不同角度增强语义理解,因此,图文语义关系挖掘是图文数据得以充分利用的关键。为解决图文数据深层语义关系挖掘不充分、检索阶段预测不精准的问题,本文提出了一种局部-全局特征引... 详细信息

具有语义相关性的文本、图像数据往往具有互补性,可以从不同角度增强语义理解,因此,图文语义关系挖掘是图文数据得以充分利用的关键。为解决图文数据深层语义关系挖掘不充分、检索阶段预测不精准的问题,本文提出了一种局部-全局特征引导的多级关系分析与挖掘方法。采用多头自注意力机制的Transformer建模图像关系,构建图像引导的文本注意力模块,挖掘图像区域和全局文本间的细粒度关系,融合局部-全局特征有效增强图文数据的语义关系。为验证本文方法,在Flickr30K、MSCOCO-1K和MSCOCO-3K数据集上进行实验,并与VSM、SGRAF等13种方法进行对比分析,本文方法中以文索图的召回率平均提升了0.62%,以图索文的召回率平均提高了0.5%,实验结果验证了本文方法的有效性。

关键词：图文关系挖掘多头自注意力机制局部-全局特征

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On time-step in structural seismic response analysis under ground displacement/acceleration

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Earthquake Engineering and Engineering Vibration 2009年第3期8卷 341-347页

作者： TianYuji~+ and Yang Qingshan~(++) School of Civil Engineering,beijing Jiaotong University,beijing 100044,China +Associate Professor ++Professor School of Civil Engineering Beijing Jiaotong University Beijing China

There are two models in use today to analyze structural responses when subjected to earthquake ground motions, the Displacement Input Model （DIM） and the Acceleration Input Model （AIM）. The time steps used in direct integration methods for these models are analyzed to examine the suitability of DIM. Numerical results are presented and show that the time-step for DIM is about the same as for AIM, and achieves the same accuracy. This is contrary to previous research that reported that there are several sources of numerical errors associated with the direct application of earthquake displacement loading, and a very small time step is required to define the displacement record and to integrate the dynamic equilibrium equation. It is shown in this paper that DIM is as accurate and suitable as, if not more than, AIM for analyzing the response of a structure to uniformly distributed and spatially varying ground motions.

关键词： integration time step multi-supported structure displacement input model acceleration input model spatially varying ground motions

Palaeogene Biostratigraphic Characteristics of Red Basins In Western Henan and Its Adjacent Areas, With an Outline of Palaeogene Palaeobiogeographic Provinces of China

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Acta Geologica Sinica(English Edition) 1992年第1期66卷 101-117页

作者： Du Hengjian Ma Ancheng Cheng Jie Wu Weimin China University of Geosciences, beijing beijing Normal University China University of Geosciences, beijing Institute of Crustal Dynamics, State Seismological Bureau, beijing China University of Geosciences Beijing China

This article is a preliminary summary of Paleogene biostratigraphy of the Liguanqiao, Tantou andYuanqu basins, with a new proposal for Paleogene paleobiogeographic provinces of China. On the basis of asynthetic analysis of the geological data, characters of the mammalian assemblages and their comparisons withother corresponding faunas, a new scheme on Paleogene biostratigraphic subdivision of the basins has been putforward here. Based on differences of biostratigraphic sequences, characteristics of mammalian assemblagesand directions of faults controlling Paleogene basins in China, six Paleogene paleobiogeographic provinces ofChina have been proposed in this paper, that is: Tianshan-Yinshan-Tumen Province; Tarim-North China Prov-ince; Kunlun-Qinling Province, Yangtze Province, Nanling and Southeastern Coastal Province, Qinghai andTibet Province.

关键词： With an Outline of Palaeogene Palaeobiogeographic Provinces of China

Application of mesoscale modeling optimization to development of advanced materials

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Progress in Natural Science:Materials International 2004年第8期14卷 8-15页

作者： SONG Xiaoyan(School of Materials Science and Engineering, beijing University of Technology, beijing 100022, China) Sch. of Materials Science and Eng. Beijing Univ. of Technology Beijing 100022 China

The rapid development of computer modeling in recent years offers opportunities for materials preparation in a more economic and efficient way. In the present paper, a practicable route for research and development of advanced materials by applying the visual and quantitative modeling technique on the mesoscale is introduced. A 3D simulation model is developed to describe the microstructure evolution during the whole process of deformation, recrystallization and grain growth in a material containing particles. In the light of simulation optimization, the long-term stabilized fine grain structures ideal for high-temperature applications are designed and produced. In addition, the feasibility, reliability and prospects of material development based on mesoscale modeling are discussed.

关键词： mesoscale computer simulation Monte Carlo technique deformation recrystallization grain growth.

Galvanic effects on cavitation damage for 1Cr13 stainless steel

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Journal of University of Science and Technology beijing 2003年第4期10卷 33-37页

作者： Dongbai Sun, Xia Bai, Hongying Yu, Huimin Meng, and Huiqing LiUNDP-beijing Corrosion and Protection Center, University of Science and Technology beijing, beijing 100083, China UNDP Corrosion Ctr. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on the electric-spark principle, a new kind of cavitation damagetesting apparatus was designed, which could produce the bubble. Bubbles collapsed and acted on asmall surface area of the alloy surface, so an intensive electrochemical inhomogenous state would beinduced and lead to the existence of surface galvanic effect on the alloy. The galvanic effect of1Cr13 SS during cavitation damage has been quantitatively investigated in NaCl solution. The resultsshow that intensive galvanic effect of 1Cr13 SS during cavitation damage appears the potential ofthe damaged area shifting negatively with the bubble collapse and simultaneously the galvaniccurrent generates. The mass loss of alloy due to cavitation increases with the bubble quantity, andincreases with the increasing of Cl- content. And both the total mass loss and the mass loss due togalvanic corrosion increase linearly with the area ratio of cavitation damaged to undamaged *** surface galvanic effects speed up the dissolution rate of the alloy, which, in turn,accelerates the mechanical damage, and aggravates the mass loss of the alloy. It has been furtherconfirmed that the mass loss due to the surface galvanic effect can be decreased by catholicprotection.

关键词： cavitation damage galvanic effect area ratio mass loss

Rate Equation of Small Particle-Air Bubble Attachment in Turbulent Flow of Flotation Cells

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 185-191页

作者： Shouci Lu Jingyong Guo(Resources Engineering School, University of Science and Technology beijing, beijing 1 00083, China) Resources Engineering School University of Science and Technology Beijing Beijing 100083 China

A rate equation of small particle-air bubble attachment in the turbulent now of flotation cells has beenderived. The equation, integrating both the collision probability and adhesion probability together, represents theprobability of attachment between particle and bubble in the turbulent flow. 'Capture efficiency' f(a) is introducedinto the rate equation to reflect the influence of energy hairier on the attachment rate. Three typical situations of particle-bubble interaction in flotation process have been discussed. For a completely hydrophobic particle-bubble system,f(a) = 1. This means that all collision leads to attachment. Whereas for hydrophilic particle-bubble systems, .f(a) =0. Thus no adhesion of particle on bubble occurs at all. In real notation circumstances, however, there always existsa certain energy barrier between the particle and the bubble. Therefore, f(a) = 0～1. In such cases, not all collisionsresult in particle-bubble attachment.

关键词： rate equation turbulent flow flotation cell capture efficiency

Recovery of functions via their irregular sampling values

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Chinese Science Bulletin 1998年第4期43卷 268-271页

作者： FANG Gensun Department of Mathematics, beijing Normal University, beijing 100875, China Department of Mathematics Lkijing Normal University Beijing China

It is proved that if a function can be completely reconstructed by tempered splines which satisfy the real Kiesz basis condition as the degree of spline goes to infinity, then the function is band limited.

关键词： band limited function cardinal splines irregular sampling.

ANALYSIS OF DEPOSITED PRODUCTS AND REANODIZED POROUS LUBRICATING FILM ON A1 AFTER(NH_4)_2MoS_4 SOLUTION TREATMENT

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 102-107页

作者： JIANG Guang WU Yinshun LI Jiuqing LIU Haiping University of Science and Technology beijing,beijing,China Department of Surface Sciences and Corrosion Engineering,University of Science and Technology beijing,beijing 100083,China beijing Univ of Science and Technology Beijing China

Observation was carried out of the structure of sulphuric,oxalic or phosphoric film on Al after treatment of reanodizing and electrolytic depositing lubricant in (NH_4)_2MoS_4 solution,as well as of the deposited products by means of EMPA,TEM and energy spectro-scopic *** deposited products are mixture of compounds of S and Mo rather than single MoS_2 and most of them dcposited near the surface layer of the *** regular long pores without barrier layer occurred in the film,but the regular fine channels without relation to the structural element parameters of original anodized film were found in the thickened barrier layer of phosphoric *** may be remained as Mo sulphide in the film during heating under Ar protective environment.

关键词： Al anodizing reanodizing lubricating film MoS_2