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Study on the stability and 3-dimensional character for natural convection in a rectangular cavity heated from below

Science china(Technological Sciences) 2010年第6期53卷 1647-1654页

作者： ZHAN NaiYan1,2,XU PeiWei1,SUN ShiMei,YANG Mo2 & LIU Jun3 1 Scool of Municipal and Environmental engineering,jilin Institute of Architectural and Civil engineering,changchun 130021,china 2 college of power engineering,university of Shanghai for Science and Technology,Shanghiai 200093,china 3 college of power engineering,jilin university,changchun 130000,china 1. Scool of Municipal and Environmental engineering Jilin Institute of Architectural and Civil Engineering Changchun 130021 China2. College of Power Engineering University of Shanghai for Science and Technology Shanghiai 200093 China3. College of Power Engineering Jilin University Changchun 130000 China

Natural convection of air is numerically simulated in a 3-dimensional rectangular cavity heated from below using SIMPLE algorithm with a QUICK *** results suggest that when all lateral walls are adiabatic,the fluid rolls occur along the long *** the Rayleigh number is smaller,the flow is of 2-dimensional character,and the rolls shapes are *** average Nusselt numbers in the central part of the cavity are *** average Nusselt numbers in the part near by the cavity are *** to the comparison of 3-dimensional results with 2-dimensional results,the flow patterns and heat transfer in the central part of the cavity can be assumed as a 2-dimensional flow,While those in the part near by the cavity can *** increasing Rayleigh number,the flow is 3-dimensional *** 3-dimensional result accords with the experimental *** all lateral walls are adiabatic,the ten rolls occur along the long *** when lateral walls are heated or cooled,the rolls disappear along the long axis and two rolls occur along the short *** rotation direction of the rolls is *** Rayleigh number is over some critical value,flow and heat transfer will be asymmetry,indicating unsteady oscillation *** nonlinear analyses,it is shown that with increasing Rayleigh number,flow and heat transfer will change from steady state to unsteady state through HOPF bifurcation,and transition to chaos will occur through multi-periodical oscillation.

关键词： Critical Raleigh number 3-dimensional character lateral boundaries nonlinear characteristic bifurcation

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Quantifying quantum entanglement via machine learning models

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Communications in Theoretical Physics 2024年第7期76卷 52-56页

作者： changchun Feng Lin Chen LMIB(Beihang university) Ministry of EducationBeijing 100191China School of Mathematical Sciences Beihang UniversityBeijing 100191China International Research Institute for Multidisciplinary Science Beihang UniversityBeijing 00191China

Quantifying entanglement measures for quantum states with unknown density matrices is a challenging *** learning offers a new perspective to address this *** training machine learning models using experimentally measurable data,we can predict the target entanglement *** this study,we compare various machine learning models and find that the linear regression and stack models perform better than *** investigate the model's impact on quantum states across different dimensions and find that higher-dimensional quantum states yield better ***,we investigate which measurable data has better predictive power for target entanglement *** correlation analysis and principal component analysis,we demonstrate that quantum moments exhibit a stronger correlation with coherent information among these data features.

关键词： quantum information entanglement predict machine learning coherence

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A software cascading faults model

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Science china(Information Sciences) 2011年第11期54卷 2454-2458页

作者： LIU YanHeng 1,2,LIU XueLian 3 & WANG Jian 1,2 1 Key Laboratory of Symbolic Computation and Knowledge engineering of Ministry of Education,jilin university,changchun 130012,china 2 college of Computer Science and Technology,jilin university,changchun 130012,china 3 college of Software,jilin university,changchun 130012,china 1. Key Laboratory of Symbolic Computation and Knowledge engineering of Ministry of Education Jilin University Changchun 130012 China2. College of Computer Science and Technology Jilin University Changchun 130012 China3. College of Software Jilin University Changchun 130012 China

Functions and call relations are extracted into nodes and edges,respectively,by which a novel topological model is *** directional edges and the corresponding weight values express the call relations and tightness *** introducing two concepts of function fault-tolerant capability and software fault intensity and by designing a allocation rule on fault-tolerant capability,a cascading fault model is built to explore fault propagation *** on practical software networks show that a weak fault intensity,a small number of initial faults,and a strong fault-tolerant capability can slow down the spreading *** functions with more call relations and more closer tightness contribute more to the stability of the whole system.

关键词： software fault tolerant cascading faults fault-tolerant capability fault intensity

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Arnold's theorem on properly degenerate systems with the Russmann nondegeneracy

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Science china Mathematics 2005年第12期48卷 1656-1669页

作者： HAN Yuecai & LI Yong college of Mathematics, jilin university, changchun 130012, china 1. college of Mathematics Jilin University 130012 Changchun China

In this paper, we investigate the persistence of invariant tori for the nearly in-tegrable Hamiltonian system H(x,y) = h(y) + εp(x,y) + ε2Q(x,y), where h(y) and εp(x,y) satisfy the Russmann non-degenerate condition. Mainly we overcome the difficulties that the order of the parameter E in the perturbation ε2Q(x,y) is not enough and that the measure estimate involves in parts of frequencies with small parameter.

关键词： Arnold’s theorem the Russmann non-degenerate condition.

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Modal extension rule

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Progress in Natural Science:Materials International 2005年第6期15卷 550-558页

作者： WU Xia*, SUN Jigui, LIN Hai and FENG Shasha(college of Computer Science and Technology, jilin university, changchun 130012, china Key Laboratory for Symbolic Computation and Knowledge engineering, jilin university, changchun 130012, china) college of Computer Science and Technology Jilin University Changchun 130012 China Key Laboratory for Symbolic Computation and Knowledge engineering Jilin University Changchun 130012 China

Modal logics are good candidates for a formal theory of agents. The efficiency of reasoning method in modal logics is very important, because it determines whether or not the reasoning method can be widely used in systems based on agent. In this paper, we modify the extension rule theorem proving method we presented before, and then apply it to P-logic that is translated from modal logic by functional transformation. At last, we give the proof of its soundness and completeness.

关键词： theorem proving extension rule modal logics functional transformation.

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Fast bowtie effect elimination for MODIS L1B data

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The Journal of china Universities of Posts and Telecommunications 2010年第1期17卷 120-126页

作者： REN Rui-zhi,GUO Shu-xu,GU Ling-jia college of electronic science and engineering,jilin university,changchun 130012,china [a] college of electronic science engineering Jilin University Changchun 130012 China

The bowtie effect refers to geometry distortions for the moderate resolution imaging spectrum-radiometer （MODIS） level 1B （L1 B） data. Till now, to eliminate the bowtie effect, numerous methods are proposed. However, most of them have limitations in computation efficiency. Through a comparative study of existing methods, this article puts forward a fast method to eliminate the bowtie effect using the ephemeris data. In this method, the rough positions of overlapping data are first detected. Because of the influence caused by the instrarnent characters and the earth＇s curvature, the positions of overlapping data need to be rectified to obtain more precise results. The optimal rectification method used in this article is selected by comparing three methods. By using the optimal method, the rectified MODIS data can be obtained. The experiments demonstrate that the bowtie effect can be eliminated in less than 1 s. In contrast, other traditional methods spend at least 3 s, thus the proposed method is faster and more effective.

关键词： bowtie effect MODIS bilinear interpolation overlapping data rectification

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Effect of Nb on the Interfacial Wettability in Al_2O_3/Medium Mn Steel

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Journal of Materials Science & Technology 2003年第6期19卷 625-627页

作者： Sirong YU, Yaohui LIU and Zhenming HEcollege of Materials Science and engineering, jilin university, changchun 130025, china college of Materials Science and engineering Jilin University Changchun 130025 China

To develop medium Mn steel (MMS) matrix composites reinforced by AI2O3 particles, the effect of Nb on the interfacial wettability of AI2O3/MMS and its mechanism were investigated in this paper. The results show that the wetting angle of the specimens with different Nb contents are bigger than that of the specimen without Nb at the first stage, and then decreases with time at 1450℃. At certain time, the wetting angle is lower than that of the specimen without Nb. At 1550 and 1600℃, the wetting angle of the specimens containing Nb decreases quickly with time at first stage. After 10 min, the wetting angle reaches a steady state, and hardly changes with time. The mechanisms of Nb to improve the wettability can be attributed to the enrichment of Nb at the interface and Nb serves as surface active agent of MMS at T3/MMS at T>1550℃, and reduces the interfacial energies.

关键词： Madium Mn steel A12O3 Nb Wettalility

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AERODYNAMIC CHARACTERISTICS ABOUT MINING DUMP TRUCK AND THE IMPROVEMENT OF HEAD SHAPE

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Journal of Hydrodynamics 2008年第6期20卷 713-718页

作者： WEI Xiu-ling WANG Guo-qiang FENG Su-li college of Mechanical Science and engineering Jilin University Changchun 130022 China Department of Aeronautic Mechanical engineering Aviation University of Air force Changchun 130022 China Fundamental Science Department Armor Technique Institute Changchun 130117 China

The external flow field around a certain mining dump truck was simulated. The airflow structure and the aerodynamic drag were discussed, and the relationship between airflow characteristics and aerodynamic drag were obtained. In order to solve the problem of head shape of the truck, three scenarios including edge rounding, installing splitter planes and their combination were put forward to improve the head shape through numerical simulation and analysis. The model and method were selected to be three dimensional and time-independent. The Reynolds-averaged Navier-Stokes equations were solved using the finite volume method. The RNG k-ε model was chosen for the closure of the turbulent quantities. The results show that the third scenario is the best one, because of its aerodynamic characteristics being better than those of unimproved model.

关键词： dump truck external flow field numerical simulation

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A Sound Quality Objective Evaluation Method Based on Auditory Peripheral Simulation Model

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Journal of Bionic engineering 2010年第2期7卷 199-208页

作者： Yinhan Gao~1,Jun Xie~2,Jie Liang~1,Xin Chang~3,Baojun Wu~2 1.Experimental Centre of Testing Science,jilin university,changchun 130022,P.R.china 2.college of Instrumentation & Electrical engineering,jilin university,changchun 130061,P.R.china 3.Laboratory of Applications and Computations in Electromagnetics and Optics,Department of Electrical engineering, university of Washington,WA 98195-2500,USA [a] Experimental Centre of Testing Science Jilin University Changchun 130022 P. R. China [b] College of Instrumentation & Electrical Engineering Jilin University Changchun 130061 P. R. China [c] Laboratory of Applications Computations in Electromagnetics Optics Department of Electrical Engineering University of Washington WA 98195-2500 USA

Based on auditory peripheral simulation model, a new Sound Quality Objective Evaluation (SQOE) method is presented,which can be used to model and analyze the impacts of head, shoulder and other parts of human body on sound wave *** method employs the artificial head technique, in which the head related transfer function was taken into account tothe outer ear simulation ***, a bionic artificial head was designed as the outer ear model with considering the outersound field in view of theory and physical *** the auditory peripheral simulation model was built, which mimicsthe physiological functions of the human hearing, simulating the acoustic signal transfer process and conversion mechanismsfrom the free field to the peripheral auditory ***, performance comparison was made between the proposed SQOEmethod and ArtemiS software, and the verifications of subjective and objective related analysis were *** show thatthe proposed method was economical, simple, and with good evaluation quality.

关键词： sound quality objective evaluation auditory peripheral simulation model artificial head head related transfer function

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PARTICLE DISTRIBUTION IN CENTRIFUGAL ACCELERATING FIELDS

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Chinese Journal of Mechanical engineering 2003年第3期16卷 329-333页

作者： Yu SirongZhang XinpingHe ZhenmingLiu Yaohuicollege of Materials Scienceand engineering,jilin university,changchun 130025, china college of Materials Science and engineering Jilin University Changchun 130025

Based on continuum theory and moving law of particles, a model is presentedto obtain gradient distribution of particles in centrifugal accelerating field, by which theparticle distribution in gradient composite material can be predicted. The simulation shows withincreases in rotating time, four regions gradually appear from the internal periphery to theexternal one, they are free region, transition region, steady region and surface reinforced region,and the latest three regions are defined as a rich region. Finally, the steady region disappears,and the rich region only includes transition region and surface reinforced region. The influences ofcentrifugal acceleration coefficient G, primary volume fraction phi_0, pouring temperature theta_pand density difference between the particle and the metal matrix on particles gradient distributionare studied in detail. The results of the theoretical analysis agree with experiment ones. Both ofanalysis and experiment results indicate that with the increase in G and theta_p the particledistribution becomes more centralized and the consistence of particle in the surface peripherybecomes larger.

关键词： Centrifugal accelerating field Particles Numerical simulation Functionalgradient material

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