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Computer Simulation of Ferrite Transformation during Hot Working of Low Carbon Steel

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Journal of Materials Science & Technology 2004年第5期20卷 497-500页

作者： Yunbo XU, Yongmei YU, Xianghua LIU and Guodong WANGState Key Laboratory of Rolling and Automation, Northeastern University, P.O. box 105, Shenyang 110004, China Lab. of Rolling and Automat. Northeastern Univ. P.O. Box 105 Shenyang 110004 China

On the basis of transformation kinetics and thermodynamics, the austenite-ferrite transformation start temperature during deformation was predicted for several grades of low-carbon steels under different processing conditions. Results indicate that Ar3d temperature mostly depended on alloying composition and processing parameters. Ar3d increased as strain rate or strain increased for the same steel grade. In view of enhancement of deformation on transformation, the basic kinetics model was established to simulate deformation induced transformation behavior, using which the influence of the deformation stored energy and effective deformation ledge on the nucleation and growth can be considered. The simulated results are in good agreement with experiment results.

关键词： Computer simulation Transformation kinetics Ultrafine ferrite Deformation induced transformation

Method for signal decomposition and denoising based on nonuniform cosine-modulated filter banks

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Progress in Natural Science:Materials International 2008年第10期18卷 1293-1298页

作者： Xuemei Xie Li Li Guangming Shi Bin Peng School of Electronic Engineering,Xidian University,Xi’an,box 134,Shaanxi 710071,China School of Electronic Engineering Xidian University Xi’an Box 134 Shaanxi 710071 China

In this paper,a novel method for signal decomposition and denoising is proposed based on a nonuniform filter bank (NUFB),which is derived from a uniform filter *** this method,the signal is firstly decomposed into M subbands using a uniform filter bank. Then according to their energy distribution,the corresponding consecutive filters are merged to compose the nonuniform *** the resulting NUFB,the signal can be readily matched and flexibly decomposed according to its power spectrum *** another advantage,this method can be used to detect and remove the narrow-band noise from the corrupted *** verify the proposed method,a simulation of extracting the main information of an audio signal and removing its glitch is given.

关键词： Signal decomposition Denoising Nonuniform filter bank Narrow-band noise

The　Realization　of　Optical　2D　Folded　Perfect　Shuffle　with　Complex　Holographic　Lens

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Chinese Journal of Lasers 1995年第1期B4卷 51-56页

作者： ZHANG Erping YU Chongxiu YAN Xiaomei XU Daxiong(Beijing University of Posts & Telecom,box.163, Beijing 100088,China) Beijing Univ of Posts & Telecom. Beijing China

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ＴｈｅＲｅａｌｉｚａｔｉｏｎｏｆＯｐｔｉｃａｌ２ＤＦｏｌｄｅｄＰｅｒｆｅｃｔＳｈｕｆｆｌｅｗｉｔｈＣｏｍｐｌｅｘＨｏｌｏｇｒａｐｈｉｃＬｅｎｓＴｈｅＲｅａｌｉｚａｔｉｏｎｏｆＯｐｔｉｃａｌ２ＤＦｏｌｄｅｄＰｅｒｆｅｃｔＳｈｕｆｆｌｅｗｉｔｈＣｏｍｐｌ...

关键词： PS (perfect shuffle) holographic optical element holographic lens//

ACTIVE VIBRATION CONTROL OF FINITE L-SHAPED BEAM WITH TRAVELLING WAVE APPROACH

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Acta Mechanica Solida Sinica 2010年第5期23卷 377-385页

作者： Chunchuan Liu Fengming Li1 Wenhu Huang(P.O.box 137,School of Astronautics,Harbin Institute of Technology,Harbin 150001,China) School of Astronautics Harbin Institute of Technology Harbin China

In this paper, the disturbance propagation and active vibration control of a finite L-shaped beam axe studied. The dynamic response of the structure is obtained by the travelling wave approach. The active vibration suppression of the finite L-shaped beam is performed based on the structural vibration power flow. In the numerical calculation, the influences of the near field effect of the error sensor and the small error of the control forces on the control results are all considered. The simulation results indicate that the structural vibration response in the medium and high frequency regions can be effectively computed by the travelling wave method. The effect of the active control by controlling the power flow is much better than that by controlling the acceleration in some cases. And the control results by the power flow method are slightly affected by the locations of the error sensor and the small error of the control forces.

关键词： finite L-shaped beam active vibration control travelling wave approach power

The asymptotic stability of multistep multiderivative methods for systems of delay differential equations

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Communications in Nonlinear Science and Numerical Simulation 2000年第1期5卷 24-26页

作者： Chengming HUANG and Qianshun CHANG Institute of Applied Mathematics, Chinese Academy of Sciences, P. O. box 2734, Beijing 100080, China Institute of Applied Mathematics Chinese Academy of Sciences P. O. Box 2734 Beijing 100080 China

This paper deals with the asymptotic stability of multistep multiderivative methods for systems of delay differential equations. In particular, it is shown that A-stability of multistep multiderivative methods for ord... 详细信息

关键词： delay differential equation stability multistep multiderivative methods

The　optimum　source－time　function　for　generating　finite－difference　synthetic　seismograms

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Acta Seismologica Sinica(English Edition) 1994年第1期7卷 23-31页

作者： Abdolrahim JAVAHERIAN(Institute of Geophysics,the University Of Tehran, P.O.box 14155-6466 Tehran,Islamic Republic of Iran) Institute of Geophysics the University of Tehran Tehran Islamic Republic of Iran

A source-time function plays an important role in generating finite-difference synthetic *** this regard,we consider the amplitude spectra of five different time *** investigation shows that when the high-frequency signals of the time function carry more power than the main signal,the tailing phenomena would be associated with the main signal which is not desirable in producing finite-difference synthetic *** is illustrated that the time function denoted by is the optimal source-time function among those examined in this paper for generating finite-difference synthetic *** matter is also verified by making finite-difference synthetic seismograms over an elastic earth model consisting of a layer over a half space.

关键词： source-time function finite-difference synthetic seismograms

Classification of highly turbid Jiaojiang Estuary

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Acta Oceanologica Sinica 1998年第4期17卷 469-482页

作者： Dong Lixian (Second Institute of Oceanography, State Oceanic Administration, P. O. box 1207, Hangzhou 310012, China) Second Institute of Oceanography State Oceanic Administration P. O. Box 1207 Hangzhou 310012 China

The Jiaoiang Estuary is shallow, macro-tidal dominated and extremely turbid, with a larger variation of the freshwater discharge. The estuarine stratification and classification are analysed by using a set of field data observed in wat *** spring tide, the depth-mean peak tidal currents can reach 2 m/s. During flood tide the water column is vertically hamogeneous, but the horizontal salinity gradient is large and there is a fresh water front. A 1 m thick fluid mud layer capped by lutocline is formed when the tidal current is less than 0. 3 m/s. As the low-salinity trapped in the fluid mud layer, underlying saltier water enhances vertical mixing when the fluid mud layer is eroded and the water column is only slishily stratified during ebb *** neap tide, the tidal currents are reduced, two lutoclines exist in the vertical profile of suspended sediment conentration (SSC ) for a long time and its positive contributions to the water column stability are 17 times larger than tha of maximum salinity gradient observed in our previous study. The water column is stratified and the fresh water front which exists in spring tide is lifted as a salt wedge in neap *** dynamics of the fine sediment is so important in the extremely turbid estuary that the estuarine classification does not fit in with the field data when the scheme of the estuarine classification proposed by Schultz and Simons (1957) is applied in the Jiaoiang Estuary.

关键词： Estuary stratification mixing fine sediment,dynamics

Structure of Thunderstorm Gust Fronts with Topographic Effects

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Advances in Atmospheric Sciences 2001年第6期18卷 1161-1174页

作者： A. A. Bidokhti and T. Bani-Hashem Institute of Geophysics, Tehran University, P.O, box 14155-6466, Tehran, LR. Iran Institute of Geopysics Tehran University

Surface meteorological observations, associated with gust fronts produced by thunderstorm outflows over Tehran, an area surrounded by mountains, have been analyzed. Distinctive features are sudden drop in air temperature, up to 10°C, sharp increase in wind speed, up to 30 m s?1, with wind shift, to northwesterly, pressure jump, up to 4 hPa, humidity increase, up to 40%, and rain after some 20 min. Gust fronts which often occur in spring time, have a typical thickness of about 1.5 km and produce vertical wind shear of the order of 10?2s?1. Although these features seem to be common for most of the events, their intensities differ from one event to another, indicating that the gust fronts may occur in different sizes and shapes. Apart from a dominant effect on the formation of the original thunderstorms, topography appears to break up the frontal structure of the gust fronts. The internal Rossby radius of deformation for these flows is small enough (～ 100 km) for rotational effects to be minor. A laboratory model of the gust front (gravity current) also shows that it initially has a distinctive head with a turbulent wake, and can be broken up by topography. It is shown that when the environment is stratified, turbulence due to lobes and clefts instabilities near the nose of the current is suppressed. When the ground is rough, these instabilities are highly amplified and the internal Froude number of the flow is reduced. The bottom slope in the presence of rough topography leads to the break up of the current head and produces a broad and highly non-uniform head, recognized in the density signals. Key words Frontal structure - Gravity current - Meteorological data - Outflows

关键词： Frontal structure Gravity current Meteorological data Outflows

One-operation image algebra for optical processing

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Chinese Journal of Lasers 1993年第4期B2卷 67-73页

作者： Liren Liu(Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, P. O. box 800-216,Shanghai 201800,China) Shanghai Inst of Optics and Fine Mechanics Shanghai China

A binary image algebra with one operation of a logic operation followed by a dilation and its modification with three additional operations for threshold processing of grey level images are developed in this paper. All the binary image processing functions and various grey level image processing functions related to morphological operations can be represented by the algebraic structure. The algebra is particularly suitable for parallel processing by optics in a cellular logic image processor architecture.

关键词： image algebra. mathematical morphology logic operations optical processing