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CO observations of massive star forming regions at different evolutionary phases

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 626-640页

作者： CHEN Xi1,2. XU Ye1,3, SHEN Zhiqiang1,3 & LI Jingjing1,2.1. shanghai Astronomical Observatory, Chinese Academy of Sciences, shanghai 2.0030,{2. 2. Graduate School of the Chinese Academy of Sciences, Beijing 100034,{2. 3. Joint Institute for Galaxy and Cosmology, shanghai Astronomical Observatory and the university of Science and Technology of{2., shanghai 2.0030,{2. shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate School of the Chinese Academy of Sciences Beijing 100034 China Joint Institute for Galaxy Cosmology Shanghai Astronomical Observatory the university of Science Technology of china Shanghai 200030 China

The 12.O (J=1-0), 13CO (J=1-0) and C18O (J=1-0) emissions in 9 massive star forming regions, which are believed to be at different stages of massive star formation, were mapped with the 13.7 m millimeter wave telescope at Qinghai Station of Purple Mountain Observatory. Of the observed 9 sources, 13CO cores were detected in seven of them, and C18O cores in five of them. And only two sources associated with C18O cores and H2. masers showed the extended structures and strong outflows. This is the first detection of outflow associated with IRAS 2.566+582. in the observing field of S152.S153. The physical parameters of cores and outflows for these sources, derived from Local Thermal Equilibrium (LTE) analysis, are presented. These observing results suggest that the C18O cores will only appear when the gas density is high enough and the probability to have an outflow is very high when the clumps show the C18O and H2. maser simulta- neously.

关键词： star formation cloud core outflow H2. maser

Strong law of large numbers for Markov chains indexed by an infinite tree with uniformly bounded degree

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Science china Mathematics 2008年第2期51卷 195-202页

作者： HUANG HuiLin~1 YANG WeiGuo~(2.) 1 Department of Mathematics,shanghai Jiaotong university,shanghai 2.02.0,china 2.Faculty of Science,Jiangsu university,Zhenjiang 2.2.13,china 1. Department of Mathematics Shanghai Jiaotong University Shanghai 200240 China 2. Faculty of Science Jiangsu University Zhenjiang 212013 China

In this paper,we study the strong law of large numbers and Shannon-McMillan (S-M) theorem for Markov chains indexed by an infinite tree with uniformly bounded *** results generalize the analogous results on a homogene... 详细信息

关键词： Markov chains Shannon-McMillan theorem strong law of large numbers uniformly bounded tree 60F15 60J10

Martensitic Transformation in Fe-Mn-Si Based Shape Memory Alloys

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Journal of Materials Science & Technology 1999年第2期15卷 111-116页

作者： T. Y. Hsu (XU Zuyao)(shanghai Jiao Tong university, shanghai 2.0030, china) shanghai Jiao Tong university Shanghai 200030 China Chinese Academy of Sciences China

The critical driving force for martensitic transformation fcc ( gamma ) yields hcp ( epsilon ) in ternary Fe-Mn-Si alloys increases with the content of Mn and decreases with that of Si. Thermodynamical prediction of M//s in ternary Fe-Mn-Si alloys was established. The fcc ( gamma ) yields hcp ( epsilon ) martensitic transformation in Fe-Mn-Si is a semi-thermoelastic and the nucleation process does not strongly depend on soft mode. Nucleation occurs directly through an overlapping of stacking fault rather than pole mechanism, and it is suggested that stacking fault energy (SFE) is the main factor controlling nucleation. Based on the phenomenological theory of martensite crystallography, a shuffle on (0001)//h//c//p plane is required when d//1//1//1 does not equal d//0//0//0//2. The derived principal strain in Bain distortion is smaller, i, e., more reasonable than the values given by Christian. Alloying elements strengthening the austenite, lowering SFE of gamma phase and reducing T//N** gamma temperature may be beneficial to shape memory effect of Fe-Mn-Si based alloys. Accordingly, Fe-Mn-Si-RE and Fe-Mn-Si-Cr-N (or Fe-Mn-Si-Ni-Cr-N) are worthy to be recommended as shape memory materials with improved shape memory effect. (Edited author abstract) 48 Refs.

关键词： Mn Martensitic Transformation in Fe-Mn-Si Based Shape Memory Alloys Fe Si

Dynamic learning rates algorithm for BPNN to forecast time series of dam security

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Progress in Natural Science:Materials International 2007年第12期17卷 1527-1530页

作者： Hu Daiping1, Wu Ruiming1, Lei Aizhong1 and Wang Qi2.1. Antai College of Economics & Management, shanghai Jiaotong university, shanghai 2.0052. china 2. Graduate School, Lanzhou university, Lanzhou 730000, china) Antai College of Economics & Management Shanghai Jiaotong University Shanghai 200052 China Graduate School Lanzhou University Lanzhou 730000 China

Time series data of dam security have a large number of observed values and should be forecasted accurately in time. Neural networks have the powerful approach ablilities of arbitrary functions and have been broadly utilized in many domains. In this paper, a dynamic learning rate training algorithm of back-propagation neural networks for time series forecasting is proposed and the networks with this algorithm are built to forecast time series of dam security. The application results demonostrate the efficiency of modelling and the effictiveness of forecasting.

关键词： neural network dynamic learning rate forecasting dam security.

Different-Periodic Travelling Wave Solutions for Nonlinear Equations

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Communications in Theoretical Physics 2004年第4期41卷 481-486页

作者： YE Li-Jun~1 LIN Ji~(1,2.1 Department of Physics,Zhejiang Normal university,Jinhua 32.004,china2.Physics Department,{2. Jiao Tong university,{2. 2.0030,china Physics Department Shanghai Jiao Tong University Shanghai 200030 China

Using Jacobi elliptic function linear superposition approach for the(1+1)-dimensional Caudrey-Dodd-Gibbon-Sawada-Kotera(CDGSK)equation and the(2.1)-dimensional Nizhnik-Novikov-Veselov(NNV)equation,many new periodic travelling wave solutions with different periods and velocities are obtained based on the knownperiodic *** procedure is crucially dependent on a sequence of cyclic identities involving Jacobi ellipticfunctions sn(ξ,m),cn(ξ,m),and dn(ξ,m).

关键词： linear superposition nonlinear equation travelling wave solution

Commission Strategy of the Auction House

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Wuhan university Journal of Natural Sciences 2006年第3期11卷 507-510页

作者： WANG Yan~ 1,2.1. College of Economics, Fudan university, shanghai 2.0433,{2. 2. School of Mathematics and Statistics, Wuhan university , Wuhan 430072. Hubei,{2. College of Economics Fudan University 200433 Shanghai China School of Mathematics Statistics Wuhan University 430072 Wuhan Hubei China

In a SIPV model, when the commission proportion is not certain, but related with bargain price, generally, it is a linear function of the bargain price, this paper gives bidders＇ equilibrium bidding strategies in the first-and secondprice auctions. We find that the equilibrium strategies in second-price auction are dominant strategies. For seller or auction house, whether the fixed proportion or the unfixed proportion is good is not only related with constant item and the linear coefficient of the linear function, the size of the fixed commission proportion, but also related with the value of the item auctioned. So, in the practical auctions, the seller and the auction house negotiated with each other to decide the commission rules for their own advantage.

关键词： auction commission proportion Bayesian equilibrium bidding strategy

GENERAL CAUCHY PROBLEM FOR THE LINEAR SHALLOW-WATER EQUATIONS ON AN EQUATORIAL BETA-PLANE

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Journal of Hydrodynamics 2006年第3期18卷 303-309页

作者： SHEN Chun SHI Wei-hui School of Mathematics and Information Yantai Normal University Yantai 264025 China shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Department of Mathematics Shanghai University Shanghai 200444 China

Based on the theory of stratification, the well-posedness of the initial value problem for the linear shallow-water equations on an equatorial beta-plane was discussed. The sufficient and necessary conditions of the existence and uniqueness for the local solution of the equations were presented and the existence conditions for formal solutions of the equations vere also given. For the Cauchy problem on the hyper-plane {t = O}, the local analytic solution were worked out and a special case was discussed. Finally, an example was used to explain the variety of formal solutions for the ill-posed problem.

关键词： stratification initial value problem,well-posedness shallow-water equations

NUMERICAL SOLUTION FOR TIDAL FLOW IN OPENING CHANNEL USING COMBINED MACCORMACK-FINITE ANALYSIS METHOD

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Journal of Hydrodynamics 2009年第4期21卷 505-511页

作者： WU Zhao-chun WANG Dao-zeng shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China School of Construction and Safety Engineering Shanghai Institute of Technology Shanghai 200235 China

A new numerical scheme for solving the tidal flow in an opening channel using the advective-diffusion shallow-water equations as the governing equations is proposed based on the combination of the MacCormack and the finite analysis methods. In the present scheme, the finite analysis method is used to discretize the momentum equation and the MacCormack technique is used to discretize the continuity equation in a single grid system. The matrix of the discretized momentum equation is characterized by predominantly main diagonal elements, which ensures favorable convergence and stability for the numerical simulation by the combined method. To verify the present method, hydraulics simulation is carried out for a section down mainstream of the Huangpu River. The computational results agree with the measured data. By use of orthogonal curvilinear coordinate system, the methods can be easily extended to the numerical simulation of the tidal flow in a tortuous channel.

关键词： MacCormack technique finite analysis method tidal flow shallow water equation numerical simulation

Computational model for perception of objects and motions

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Science china(Life Sciences) 2008年第6期51卷 526-536页

作者： YANG WenLu1,2. ZHANG LiQing1 & MA LiBo1 1 Department of Computer Science and Engineering, shanghai Jiao Tong university, shanghai 2.02.0, china 2.Department of Electronic Engineering, shanghai Maritime university, shanghai 2.0135, china 1. Department of Computer Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China 2. Department of Electronic Engineering Shanghai Maritime University Shanghai 200135 China

Perception of objects and motions in the visual scene is one of the basic problems in the visual system. There exist 'What' and 'Where' pathways in the superior visual cortex, starting from the simple cells in the primary visual cortex. The former is able to perceive objects such as forms, color, and texture, and the latter perceives 'where', for example, velocity and direction of spatial movement of objects. This paper explores brain-like computational architectures of visual information processing. We propose a visual perceptual model and computational mechanism for training the perceptual model. The compu- tational model is a three-layer network. The first layer is the input layer which is used to receive the stimuli from natural environments. The second layer is designed for representing the internal neural information. The connections between the first layer and the second layer, called the receptive fields of neurons, are self-adaptively learned based on principle of sparse neural representation. To this end, we introduce Kullback-Leibler divergence as the measure of independence between neural responses and derive the learning algorithm based on minimizing the cost function. The proposed algorithm is applied to train the basis functions, namely receptive fields, which are localized, oriented, and bandpassed. The resultant receptive fields of neurons in the second layer have the characteristics resembling that of simple cells in the primary visual cortex. Based on these basis functions, we further construct the third layer for perception of what and where in the superior visual cortex. The proposed model is able to perceive objects and their motions with a high accuracy and strong robustness against additive noise. Computer simulation results in the final section show the feasibility of the proposed perceptual model and high efficiency of the learning algorithm.

关键词： visual perception visual cortex computational model receptive fields simple cells complex cells