检索结果-南通市图书馆

OPTIMIZING LAYOUT OF URBAN STREET CANYON USING NUMERICAL SIMULATION COUPLING WITH MATHEMATICAL OPTIMIZATION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第3期18卷 345-351页

作者： WANG Jia-song ZHAO Bao-qing YE Chun YANG De-qing HUANG Zhen school of Mechanical and Power engineering Shanghai Jiaotong University Shanghai 200030 China school of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China

Optimizing the layout of the urban street canyon to achieve the maximum environmental benefits should become a new idea for modem urban street design and planning. This paper aims to find out the optimized street canyon from a viewpoint of environmental protection by using the two-dimensional numerical simulation model with the κ-ω turbulence model, coupling with the mathematical optimization method. The total pollutant concentration within and at top of the specific street canyons was taken as the objective function, and the height of one side of the canyon as the constrained condition. A nonlinearly improved constrained variable metric solver was used. The effect of the height of the leeward building and windward building on the integrated pollutant dispersion was studied to achieve the most beneficial configuration of the urban geometry. The optimization of layout for an asymmetrical street canyon was obtained. It is further found that the step-down street canyon with a large height difference is generally a good layout favoring to reduce the concentration accumulation in the street canyon.

关键词： street canyon mathematical optimization numerical simulation street layout

An accessibility measure for the combined travel demand model

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第2期53卷 299-306页

作者： YANG Chao & HE ShuLin school of Transportation engineering, Tongji university, shanghai 201804, china school of Transportation engineering Tongji University Shanghai China

The accessibility-oriented transport planning method is critical for many high population density cities in china. Most definitions of accessibility only consider spatial separation and ignore the influence of traveler choice on accessibility. In this paper, the combined travel demand model is employed in transport planning. The travelers’ choice behavior of the model is based on the random utility theory. The model overcomes inconsistence problem of the sequential four-step model on travel behavior and congestion effects. Based on the same random utility theory, an accessibility measure is proposed, which can be integrated into the combined travel demand model. The accessibility measure can reflect the traveler’s choices at different stages (travel choice, destination choice, mode choice and route choice). The properties of the accessibility measure are discussed through a numerical example.

关键词： accessibility random utility theory combined travel demand model urban transport planning

Fold-Hopf bifurcation in a simplified four-neuron BAM (bidirectional associative memory) neural network with two delays

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第3期53卷 633-644页

作者： GE JuHong & XU Jian school of Aerospace engineering and Applied Mechanics,Tongji university,shanghai 200092,china school of Aerospace engineering and Applied Mechanics Tongji University Shanghai China

The bidirectional associative memory (BAM) neural network with four neurons and two delays is considered in the present paper.A linear stability analysis for the trivial equilibrium is firstly employed to provide a possible critical point at which a zero and a pair of pure imaginary eigenvalues occur in the corresponding characteristic equation.A fold-Hopf bifurcation is proved to happen at this critical point by the nonlinear *** coupling strength and the delay are considered as bifurcation parameters to investigate the dynamical behaviors derived from the fold-Hopf *** dynamical behaviours are qualitatively classified in the neighbourhood of the fold-Hopf bifurcation point by using the center manifold reduction (CMR) together with the normal *** bifurcating periodic solutions are expressed analytically in an approximate *** validity of the results is shown by their consistency with the numerical simulation.

关键词： codimension-two bifurcation time delay solution classification unfolding centre manifold

NUMERICAL SIMULATION OF TWO-DIMENSIONAL OVERTOPPING AGAINST SEAWALLS ARMORED WITH ARTIFICIAL UNITS IN REGULAR WAVES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第3期19卷 322-329页

作者： LU Yong-jin LIU Hua WU Wei ZHANG Jiu-shan school of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China shanghai Hydraulic engineering Design and Research Institute Shanghai 200063 China school of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China

A new mathematical model for the overtopping against seawalls armored with artificial units in regular waves was established. The 2-D numerical wave flume, based on the Reynolds Averaged Navier-Stokes （RANS） equations and the standard κ-ε turbulence model, was developed to simulate the turbulent flows with the free surface, in which the Volume Of Fluid （VOF） method was used to handle the large deformation of the free surface and the relaxation approach of combined wave generation and absorbing was implemented. In order to consider the effects of energy dissipation due to the armors on a slope seawall, a porous media model was proposed and implemented in the numerical wave flume. A series of physical model experiments were carried out in the same condition of the numerical simulation to determine the drag coefficient in the porous media model in terms of the overtopping discharge. Compared the computational value of overtopping over the seawall with the experimental data, the values of the effective drag coefficient was calibrated for the layers of blocks at different locations along the seawalls.

关键词： porous media overtopping seawall armored units 2-D numerical wave flume regular waves

The Absorption Characteristics of Inhomogeneous Double-Clad Fibers

在线全文

学校读者我要写书评

暂无评论

光学学报 2003年第S1期23卷 70-71页

作者： Hui Zhang Zihua Wang Zhongyin Xiao (school of Communication and Information engineering, shanghai university, shanghai, 200072, P.R.china school of Communication and Information engineering Shanghai University Shanghai 200072 P.R.China

The absorption characteristics of radially inhomogeneous double-clad fiber (DCF) are investigated firstly with the method of caustic radius, combined with the method of WKBJ. The results are significant for double-cla... 详细信息

关键词： of et In as The Absorption Characteristics of Inhomogeneous Double-Clad Fibers mode DCF for into

A new scheme of digital communication using chaotic signals in MIMO channels

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2012年第10期55卷 2183-2193页

作者： MA HuanFei 1 & KAN HaiBin 2 1 school of Mathematical sciences,Soochow university,Suzhou 215006,china 2 school of computer science,Fudan university,shanghai 200433,china school of Mathematical sciences Soochow University Suzhou China school of computer science Fudan University Shanghai China

This paper proposes a new digital communication scheme,which uses chaotic signals based on the adaptive synchronization and parameter identification technique of chaotic systems reported *** to the multi signal character,this scheme combines the chaotic signal transmission with the MIMO channel technique in a wireless environment,which is different from the traditional chaotic communication *** a practical perspective,an outline of modulation,channel model,demodulation and non-coherent detection is ***,system performance is evaluated by simulations,and improvements on this scheme are also discussed.

关键词： chaotic modulation chaotic digital communication mapping parameters MIMO channel

SIMULATION OF LAGRANGIAN DISPERSION USING A LAGRANGIAN STOCHASTIC MODEL AND DNS IN A TURBULENT CHANNEL FLOW

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第6期21卷 767-773页

作者： LUO Jian-ping LU Zhi-ming LIU Yu-lu school of Mechanical and Automation engineering Shanghai Institute of Technology Shanghai 200235 China shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The mean square displacements of fluid particles in a turbulent channel flow at Reτ = 100 are investigated using a modified Langevin equation, and are compared with DNS results. Both the Lagrangian integral time scales directly obtained from DNS and the predicted values using an empirical relation between the Eulerian and the Lagrangian integral time scales are used in the modified Langevin equation to test the effects of integral time scales on the dispersion of particles. The results show that the slight variation of the Lagrangian integral time scale has little influence on the dispersion. The agreement between results of the model equation and those of DNS is satisfactory except the streamwise dispersion for intermediate times （ 20 〈 t^＋〈 300 ）, where the results of the model equation are slightly overestimated compared to those of DNS. The cause of such discrepancy is discussed.

关键词： turbulent channel flow Lagrangian dispersion Lagrangian stochastic model

Fusion Protein of Interleukin 4 and Diphtherial Toxin with High Cytotoxicity to Cancer Cells

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第6期36卷 437-442页

作者： Yu-Jian ZHANG, Xiao-BoHU, Su-Xia LI1, Li-Ping TIAN, Sheng-Li YANG, and Yi GONG* Research Center of Biotechnology, shanghai Institutes for Biological sciences,Chinese Academy of sciences, Graduate school of the Chinese Academy of sciences, shanghai 200233, china State Key Laboratory of Bioreactor engineering, East china university of science and Technology, shanghai 200237, china Research Center of Biotechnology Shanghai Institutes for Biological SciencesChinese Academy of Sciences Graduate School of the Chinese Academy of SciencesShanghai 200233 China State Key Laboratory of Bioreactor engineering East China University of Science and TechnologyShanghai 200237 China

Receptor of human interleukin 4 (hIL4R) has been found to be present on many types of cancer, so it may be a good target for cancer therapy. Here, fusion toxin gene DT4H has been constructed by fusing DNA sequence encoding the first 389 amino acids of diphtherial toxin (DT), which can not bind its own receptor, to human interleukin 4 (hIL4) gene. In order to improve the affinity of fusion toxin for hIL4R, a circularly permuted form of hIL4 (cpIL4) was used. The fusion gene was expressed in Escherichia coli where the fusion toxin DT4H was highly expressed. Purified DT4H was very cytotoxic to cancer cell line U251 cells, and moderate cytotoxic to HepG2 and MCF-7 cells. SGC-7901 cells were insensitive to it. The cytotoxic action of DT4H was specific because it was blocked by excess hIL4. These results suggest that DT4H may be a useful agent in the treatment of certain malignancies.

关键词： fusion toxin diphtherial toxin cancer therapy interleukin 4 IL-4 receptor

Chemical Extraction Preparation of Delithiated Cathode Materials of Li-ion Battery

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials science) 2009年第6期24卷 863-866页

作者：闫时建 school of Materials science and engineering Taiyuan University of Science and Technology

A method of conventional chemical reaction to prepare delithiated cathode materials of Li-ion battery was introduced. The cathode material of Li-ion battery was mixed with oxidizing agent Na2S2O8 in water solution, and the solution was stirred continuously to make the chemical reaction proceed sufficiently, then the reaction product was filtered and finally the insoluble delithiated cathode material was obtained. A series of tests were conducted to verify the composition, crystal structure and electrochemical property of the delithiated cathode materials were all desirable. This method overcomes the shortcomings of battery charging preparation and chemical extraction preparation employing other oxidizing agents.

关键词： chemical extraction delithiated cathode material Li-ion battery