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

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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

Effect of Sintering Aid CuO-MnO_2 on Dielectric Properties of 0.5Ba(Mg_(1/3)Nb_(2/3))O_3-0.5Ba(Ni_(1/3)Nb_(2/3))O_3 Ceramics

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Journal of Wuhan university of Technology(Materials Science) 2009年第1期24卷 123-126页

作者：田中青 School of Materials Science and engineering Chongqing Institute of Technology

Microstructures and microwave dielectric properties of 0.5Ba（Mg1/3Nb2/3）O3-0.5Ba（Ni1/3Nb2/3）O3 ceramics with x wt% CuO-x wt% MnO2 additions （x=0.25-1） prepared by conventional solid-state route were investigated. It is found that low level-doping of CuO-MnO2 can significantly improve the density of the specimens and their microwave dielectric properties. The relative density of 0.5Ba（Mg1/3Nb2/3）O3-0.5Ba（Ni1/3Nb2/3）O3 ceramics can be increased by 95% sintering at 1 330 ℃ due to the liquid phase effect. The second phase is not observed in ceramics with CuO-MnO2 addition. The parameterεr increases with increasing sintering temperature, and Qf is effectively promoted by CuO-MnO2 addition. Higher CuO-MnO2 content would make τf value more positive. Meanwhile, εr value of 30.5, Qf value of 63 200 GHz and τf value of 0.5 ppm/ ℃ were obtained for 0.5Ba（Mg1/3Nb2/3）O3-0.5Ba（Ni1/3Nb2/3）O3 ceramics with 0.5 wt% CuO-0.5 wt% MnO2 addition sin-tered at 1 330 ℃ for 4 h.

关键词： ceramics oxides X-ray diffraction dielectric properties

A two-dimensional study on natural convection and heat transfer in the enclosure with heat transfer and radiation coupled in natural convection

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Science china(Technological Sciences) 2010年第4期53卷 991-999页

作者： ZHAN NaiYan1,2,YANG Mo1 & XU PeiWei2 1 College of power engineering,university of Shanghai for Science and Technology,Shanghiai 200093,china 2 Department of Environmental engineering,Jilin Architectural and Civil engineering institute,Changchun 130021,china 1. College of power engineering University of Shanghai for Science and Technology Shanghiai 200093 China2. Department of Environmental Engineering Jilin Architectural and Civil Engineering Institute Changchun 130021 China

Numerical investigation using SIMPLE algorithm with QUICK scheme for natural convection and heat transfer in the enclosure bounded by a solid wall and with heat transfer and radiation coupled in natural convection has been *** various parameters are:Rayleigh number(from 103 to 105),dimensionless conductivity of bounding wall(from 0 to 100),dimensionless wall thickness(from 0 to 0.6) and radiation emissivity of all surfaces(from 0 to 1).The results suggest that flow and heat transfer are influenced by *** is a dominant action on flow and heat *** increase of the thermal conductivity of wall,flow and heat transfer turn *** temperature distribution changes *** the thermal conductivity of wall is over a certain critical number,the increasing trend of flow and heat transfer may *** increase of enclosure wall thickness,flow and heat transfer turn *** the enclosure wall thickness is over a certain critical number,the flow and heat transfer will turn slow.

关键词： conduction natural convection radiation couple numerical simulation

Tracking Control and Synchronization for Two-Dimension Discrete Chaotic Systems

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The Journal of china Universities of Posts and Telecommunications 2002年第3期9卷 7-10页

作者： CHEN Xi ming, ZHOU Ping (institute of Electronic engineering, chongqing university of Posts and Telecommunications, chongqing 400065, P.R.china) institute of Electronic engineering Chongqing University of Posts and Telecommunications Chongqing 400065 P. R. China

The popular method of tracking control and synchronization for two-dimensiondiscrete chaotic systems is put forward in this paper, and the chaotic system track arbitrarilyreference signal is realized. This method is a... 详细信息

关键词： discrete chaotic systems tracking control reference signal

Unified solutions for stresses and displacements around circular tunnels using the Unified Strength Theory

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Science china(Technological Sciences) 2010年第6期53卷 1694-1699页

作者： ZHANG ChangGuang1,WANG JiangFeng2 & ZHAO JunHai3 1 Department of Geotechnical engineering,Tongji university,Shanghai 200092,china 2 North china institute of Water Conservancy and Hydroelectric power,Zhengzhou 450011,china 3 School of Civil engineering,Chang’an university,Xi’an 710061,china 1. Department of Geotechnical engineering Tongji University Shanghai 200092 China2. North China Institute of Water Conservancy and Hydroelectric Power Zhengzhou 450011 China3. School of Civil Engineering Chang’an University Xi’an 710061 China

The unified solutions are presented for stresses and displacements around a circular tunnel subjected to a hydrostatic stress *** rock mass is assumed to be elastic-brittle-plastic and governed by the Unified Strength *** displacements are obtained accounting for three different definitions for elastic strains and different Young's modulus in the plastic *** unified solutions obtained in this paper are especially versatile in reflecting the intermediate principal stress effect to different extents for different *** conventional solutions,based on the Mohr-Coulomb failure criterion and the Generalized Twin Shear Stress yield criterion,are special cases of the present unified *** new unified solutions can compare with those computed by the latest generalized Hoek-Brown failure *** results obtained demonstrate the importance of the intermediate principal stress influence for the stresses and displacements *** effects of different definitions for elastic strains and different Young's modulus in the plastic zone on the displacements are significant.

关键词： Unified Strength Theory intermediate principal stress different definitions for elastic strains different Young’s modulus

Adsorption difference of Pb^(2+) and Zn^(2+) in sandstone and breccia

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Rare Metals 2002年第1期21卷 56-61页

作者： XULongjun MUChuanlong XIANXuefu instituteofMineengineeringPhysics ChongqingUniversityChongqing400044China ChengduinstituteofGeologyandMineralResources Chengdu610082China KeyLab.fortheExploitationofSouthwestResourcesandEnvironmentalDisasterControlengineeringofMinistryofEducation ChongqingUniversityChongqing400044China

The adsorption difference of Pb^2_+ and Zn^2+ in sandstone andbreccia of Pb-Zn Mine of Yunnan Province was studied by using moderninstrument analysis method and fractal geometry theory. The resultsshow that the adsorption capacity (Q) of Pb^2+ in this two rocks isbigger than that of Zn^2_+, and Q in various initial concentrationsolutions obeys Freundlich experiential formula. The value of 1/n onthe adsorption PB^2+ and Zn^2+ and Zn^2+ in sandstone hardly has anydifference, But the value of k differs observably.

关键词： adsorption Pb^2^+ sandstone breccia

Alternative Theorems and Sufficient Conditions of Global Convergence for a Class of Feasible Direction Algorithms

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Systems Science and Systems engineering 1993年第3期3卷 266-272页

作者： ZHAO Yunbin chongqing Industry and Management institute, chongqing 630050, china

In this paper, two alternative theorems which differ from Theorem 10.2.6 in [1] and Theorem 1 in [3] are presented for a class of feasible direction algorithms. On the basis of alternative theorems, furthermore, two s... 详细信息

关键词： alternative theorem feasible direction algorithm sufficiently certain function global convergence gradient projection.

支持新型储能发展的国际政策与中国发展模式探讨

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电网技术 2024年第2期48卷 469-479页

作者：胡江溢杨高峰宋兆欧康重庆国网重庆市电力公司重庆市渝中区400015 清华大学电机工程与应用电子技术系北京市海淀区100084

大力发展新型储能对支撑新能源消纳,提升电力系统调节能力,构建新型电力系统具有重大意义。在深入研究新型储能产业国内外发展现状以及支撑政策导向的基础上,以重庆电网为例,对我国省级电网新型储能发展3个方面的需求及现状开展分析,同... 详细信息

大力发展新型储能对支撑新能源消纳,提升电力系统调节能力,构建新型电力系统具有重大意义。在深入研究新型储能产业国内外发展现状以及支撑政策导向的基础上,以重庆电网为例,对我国省级电网新型储能发展3个方面的需求及现状开展分析,同时进一步研究并指出当前新型储能盈利模式以及推动其规模化发展所面临的3个主要问题。最后从推动系统友好型“新能源+储能”发展模式、以多元化激励模式加大储能政策支持力度、从多类型市场出发完善储能交易机制3个方面提出解决思路建议,以促进新型储能产业健康发展。

关键词：新型能源体系新型储能发展新能源市场机制

维普期刊数据库博看期刊

GROWTH MODE AND MODIFICATION OF GRAPHITE IN CAST IRON MELT

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Acta Metallurgica Sinica(English Letters) 1992年第10期5卷 263-267页

作者： LIU Yongkun Southwestern institute of Technology and engineering,chongqing,chinaYANG Shihao Shandong Polytechnical university,Jinan,china

Using liquid quenching technique,the change of growth mode of graphite in cast iron melt was *** on the interface structure theory of crystal growth,the concept of multiplication of spiral growth steps was advanced and two basic multiplication models were *** was proposed that multiplication of spiral steps is responsible for the change of growth mode of graphite in cast iron *** modifying elements such as Ce promote multiplication of spiral steps,which is regarded as the core of *** of screw dislocation and branch of the sector blocks in radius direction,both of which are essential to spheroidization of graphite in the melt,are caused by multiplication of spiral steps:and so is thickening of graphite plates.

关键词： graphite crystallization morphology growth mode spiral growth seeps cast iron