检索结果-南通市图书馆

Journal of Hydrodynamics 2008年第1期20卷 54-59页

作者： ZENG Zhuo-xiong Aeronautic and Mechanical Engineering College Nanchang Hangkong University Nanchang 330063 China

A semi-empirical turbulence enhancement model accounting for the particle-wake effect was incorporated into the second-order moment two-phase turbulence model and employed to simulate gas-particle flows in a swirling sudden-expansion chamber. The simulated results for two-phases mean velocities and fluctuation velocities coincide well with the experiment ones, which demonstrates that this model, in comparison with the turbulence model not accounting for the wake effect, leads to higher calculating accuracy.

关键词： gas-particle flows turbulence modulation particle wake effect

A SECOND-ORDER MOMENT TURBULENCE MODEL FOR POWER LAW FLUID WITH PARTICLES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第5期19卷 607-612页

作者： ZENG Zhuo-xiong PAN Yang ZHONG Chun QIU Guo-bin Aeronautic and Mechanical Engineering College Nanchang Hangkong University Nanchang 330063 China School of Civil Engineering and Architecture East China Jiaotong University Nanchang 330013 China

The USM-θ model of power law fluid for dense two-phase turbulent flow was developed, which combines the unified second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. This model was used to simulate the turbulent flow of power law fluid single-phase in pipe. It is shown that the USM- θ model has better prediction result than the κf -κf - κ- εp -θ model. The USM-O model was then used to simulate the dense two-phase turbulent up flow of power law fluid with particles. With the increase of the flow exponent, the velocities of power law fluid and particles increase near the pipe centre. Comparison between the two-phase flow of power law fluid-particle and of liquid-particle indicates that the axial fluctuation velocity of fluid phase and particle phase in liquid-particle two-phase flow is smaller than that in the power law fluid two-phase flow, but the two-phase velocities of power law fluid-particle and liquid-particle are close to each other.

关键词： power law fluid two-phase flow second-ordermoment turbulence model

NUMERICAL SIMULATION OF GAS TURBULENCE ENHANCEMENT BY PARTICLE-WAKE EFFECT

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第2期19卷 155-159页

作者： ZENG Zhuo-zhi ZENG Zhuo-xiong NAN Ying HAN Shou-lei Aeronautic and Mechanical Engineering college Nanchang University of Aeronautics Nanchang 330063 China

A new turbulence enhancement model was incorporated into the second-order moment two-phase turbulence model and was used to simulate gas-particle flows in swirling chambers and channels with different wall roughness. The results show that compared with the turbulence modification model not accounting for the wake effect, this model, together with the conventional particle source term, gives simulation results in better agreement with the experimental data.

关键词： gas-particle flows turbulencemodification numerical simulation

Support vector classification algorithm based on variable parameter linear programming

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第2期18卷 355-359页

作者： Xiao Jianhua Lin Jian Systems science and Technology Inst. Wuyi Univ. Jiangmen 529020 P. R. China School of Economy and Management Beijing Univ. of Aeronautics and Astronautics Beijing 100083 P. R. China

To solve the problems of SVM in dealing with large sample size and asymmetric distributed samples, a support vector classification algorithm based on variable parameter linear programming is proposed. In the proposed algorithm, linear programming is employed to solve the optimization problem of classification to decrease the computation time and to reduce its complexity when compared with the original model. The adjusted punishment parameter greatly reduced the classification error resulting from asymmetric distributed samples and the detailed procedure of the proposed algorithm is given. An experiment is conducted to verify whether the proposed algorithm is suitable for asymmetric distributed samples.

关键词： Support vector machine Linear programming Classification Variable parameter.

A NEW TURBULENCE MODULATION IN SECOND-ORDER MOMENT TWO-PHASE MODEL AND ITS APPLICATION TO HORIZONTAL CHANNEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第3期20卷 331-338页

作者： ZENG Zhuo-xiong Aeronautic and Mechanical Engineering College Nanchang Hangkong University Nanchang 330063 China

A new second-order moment two- phase turbulence model accounting for particle wake effect was established and used to simulate gas-particle flow in a horizontal channel for different values of wall roughness. The results show that compared with the model without considering the particle wake effect, the present model gives simulation results agreeing much better with the experimental results for the gas turbulence modulation, but the predicted results for particle motion with the two kinds of models are quite close.

关键词： gas-particle flows turbulence modification numerical simulation

Synchronization of chaos using radial basis functions neural networks

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第1期18卷 83-88,100页

作者： Ren Haipeng Liu Ding School of Automation and Information Engineering Xi'an Univ. of Technology Xi'an 710048 P.R.China

The Radial Basis Functions Neural Network （RBFNN） is used to establish the model of a response system through the input and output data of the system. The synchronization between a drive system and the response system can be implemented by employing the RBFNN model and state feedback control. In this case, the exact mathematical model, which is the precondition for the conventional method, is unnecessary for implementing synchronization. The effect of the model error is investigated and a corresponding theorem is developed. The effect of the parameter perturbations and the measurement noise is investigated through simulations. The simulation results under different conditions show the effectiveness of the method.

关键词： Chaos synchronization Radial basis function neural networks Model error Parameter perturbation Measurement noise.

A NEW FAMILY OF FILTRATION s+6 IN THE STABLE HOMOTOPY GROUPS OF SPHERES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2006年第2期26卷 193-201页

作者：刘秀贵 School of Mathematical sciences and LMPC Nankai University Tianjin 300071China

In the year 2002, Lin detected a nontrivial family in the stable homotopy groups of spheres ;π-6S which is represented by hngoγ^-3 ∈ Ext^6tA（Zp, Zp） in the Adams spectral sequence, where t = 2p^n（p- 1）＋ 6（p^2 ＋p ＋ 1）（p- 1） and p ≥ 7 is a prime number. This article generalizes the result and proves the existence of a new nontrivial family of filtration s ＋ 6 in the stable homotopy groups of spheres πt1-8-6S which is represented by bygoγ^s＋3 ∈ Ext^s＋6＋t1Atl （Zp, Zp） in the Adams spectral sequence, where n≥ 4, 0 ≤ s 〈 p - 4, t1 = 2p^n（p- 1）＋ 2（p- 1）（（s ＋ 3）p^2 ＋（s ＋ 3）p ＋（s ＋ 3））＋ s.

关键词： Stable homotopy groups of spheres Adams spectral sequence Toda-Smith spectrum May spectral sequence

THE BLUE AND MINQUE IN GAUSS-MARKOFF MODEL WITH LINEAR TRANSFORMATION OF THE OBSERVABLE VARIABLES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2007年第1期27卷 203-210页

作者：张宝学 Department of Statistics Northeast Normal University

For a singular linear model A = （y, Xβ, σ2 V） and its transformed model MF = （Fy, FXβ, σ 2FVF＇）, where V is nonnegative definite and X can be rank-deficient, the expressions for the differences of the estimates for the vector of FXβ and the variance factor σ2 are given. Moreover, the necessary and sufficient conditions for the equalities of the estimates for the vector of FXβ and the variance factor σ2 are also established. In the meantime, works in Baksalary and Kala （1981） are strengthened and consequences in Puntanen and Nurhonen （1992）, and Puntanen （1996） are extended.

关键词： Singular linear model BLUE MINQUE linear transformation

A secure and high-performance multi-controller architecture for software-defined networking

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2016年第7期17卷 634-646页

作者： Huan-zhao WANG Peng ZHANG Lei XIONG Xin LIU Cheng-chen HU Department of Computer science and Technology Xi'an Jiaotong UniversityXi'an 710059China science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory Shijiazhuang 050081China MOE Key Laboratory for Intelligent Networks and Network Security Xi'an Jiaotong UniversityXi'an 710049China

Controllers play a critical role in software-defined networking(SDN).However,existing singlecontroller SDN architectures are vulnerable to single-point failures,where a controller's capacity can be saturated by flooded flow requests.In addition,due to the complicated interactions between applications and controllers,the flow setup latency is relatively large.To address the above security and performance issues of current SDN controllers,we propose distributed rule store(DRS),a new multi-controller architecture for SDNs.In DRS,the controller caches the flow rules calculated by applications,and distributes these rules to multiple controller instances.Each controller instance holds only a subset of all rules,and periodically checks the consistency of flow rules with each other.Requests from switches are distributed among multiple controllers,in order to mitigate controller capacity saturation attack.At the same time,when rules at one controller are maliciously modified,they can be detected and recovered in time.We implement DRS based on Floodlight and evaluate it with extensive emulation.The results show that DRS can effectively maintain a consistently distributed rule store,and at the same time can achieve a shorter flow setup time and a higher processing throughput,compared with ONOS and Floodlight.

关键词： Software-defined networking(SDN) Security Multi-controller Distributed rule store

Practical Paths towards Lowering Black Carbon Emissions

在线全文

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2011年第1期2卷 12-22页

作者： Guorui Zhi Xiaoye Zhang Hongbing Cheng Junli Jin Fang Zhang Tingting Wang Xiaochun Zhang Chinese Academy of Meteorological sciences ChiTta Meteorological Administration Bcijing 100081 China

黑碳(BC ) 喷雾器，为大气的喷雾器的次要的部分的财务，在空气质量，人的健康，和气候变化上由于它的影响正在吸引增加的注意。集中于 BC 排放减小，这份报纸把简短介绍给来源和 BC 的全球分发。与从象全球温室气体( GHG )和调整本地... 详细信息

黑碳(BC ) 喷雾器，为大气的喷雾器的次要的部分的财务，在空气质量，人的健康，和气候变化上由于它的影响正在吸引增加的注意。集中于 BC 排放减小，这份报纸把简短介绍给来源和 BC 的全球分发。与从象全球温室气体( GHG )和调整本地空气质量的减小的如此的行动的 BC 排出物的减少一起，它也加亮象燃烧条件的控制和改进那样的另外的 BC 减小途径，开的生物资源烧的消除，并且由生物资源热分解的 BC 的隐遁。最后，在这时刻，没有足够的原因推 BC 减小进任何气候变化，这被强调联系了协商，尽管 BC 为对气候和非气候呼吁的快反应在一些所谓的双赢减小目标被包括了。引证 Zhi， G. ， X. 张， H。Cheng，等， 2011：向阴沉的黑碳排出物的实际路径。副词。Clim。变化物件， 2 (1 ) ， doi：10.3724/SP .J.1248.2011.00012。

关键词：碳烟排放大气气溶胶气候变化空气质量温室气体燃烧条件生物质热解人体健康