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An accessibility measure for the combined travel demand model

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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,{3. 1. school of Transportation Engineering Tongji University Shanghai 201804 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

Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

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Journal of Wuhan university of technology(Materials science) 2009年第4期24卷 515-519页

作者：张津 school of Materials science & Engineering University of Science and Technology Beijing College of Materials science & Engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

Redistribution of Boron during Ferrite Reaction in Nb-B Microalloyed Steel

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 223-227页

作者： Shanwu Yang Xinlai He(Applied science school, university of science and technology Beijing, Beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

By contrast of microstructure and boron distribution in the same area of samples, the behavior of boronduring ferrite reaction in Nb-B microalloyed steel was studied. Boron atoms have segregated to original austeniteboundaries betfore ferrite reaction starts during isothermal treatment. The concentration of boron in small Pieces offerrite foming along austenite boundaries may be remarkably higher than that in austenite matrix, but it will reducegradually when the ferrite continuously grows. There is no obvious boron segregation on interface of γ/α and α/α.These facts indicate that ferrite growth is not controlled by diffusion of boron in austenite.

关键词： boron segregation ferrite reaction microalloyed steel

Recycling of Spent Nickel-Cadmium Batteries

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 126-131页

作者： Xanghua Kong Pingnan Wu(Metallurgy school, university of science and {3. Beijing, Beijing 100083. china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

A technique for recycling spent nickel-cadmium batteries, which makes separaion of cadmium and nickel possible, is developed by laboratory-scale experiments. NH3.H2CO3.aqueous solution was used in this leaching technique. Since neutralization and/or solvent extraction were not required in the separation procedure of nickel and cadmium, the closed systemizaion of the process becomespossible. Experimental results show that, (1) if the NH3.concentraion of leaching solution is sufficiently high and the ratio of H2CO3.toNH3.is properly adjusted, both Ni(OH)2 and Cd(OH)2 react with NH, and quickly dissolve into leaching solution, and (2) Ni(OH)2 can beconverted into insoluble NiO by calcination at 500℃, and CdO from Cd(OH)2 by calcination maintains good solubility in NH3.H2CO3.queous solution. As a conclusion, the recycling technique characterized by two step leaching can be developed based on such changesin dissolution behavior by calcination. Meanwhile, the yields of 99.8% for nickel and 97.6% for cadmium are obtained, and the puritiesof Recycling of Spent Nickel-Cadmium BatterieRecycling of Spent Nickel-Cadmium Batteries Recycling of Spent Nickel-Cadmium Batteriesrecovered nickel and cadmium are 99.9% and 98.6%, respectively.

关键词： nickel-cadmium batteries recycling, ammonia leaching closed system environmental protection

Comparison of Some Methods on Prediction of Activity Interaction Coefficient

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International Journal of Minerals,Metallurgy and Materials 1998年第1期12卷 13-15页

作者： Changxiang Xiang Ningxin Zhang (Applied science school, university of science and technology Beijing, Beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

Based on Miedema's semiempirical formation enthalpy model for binary alloys, free volume theory and ageneral solution model, a new model for prediction of activity interaction coefficient ε is proposed. The calculatedresults are better in agreement with the experimental values than the two previous models. The related theories andmodels are discussed according to the degree of agreement with experimental values.

关键词： Miedema's semiempirical formation enthalpy model activity interaction coefficient free volume theory similarity coefficient

Equilibrium Precipitation of Niobium Carbonitride in Austenite

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 119-122页

作者： Fuming Wang Wenchao Li(Applied science school, university of science and technology Beijing, Beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

The equilibrium between niobium carbonitride and austenite has been studied. Experimentally, X-raydiffaction technique was adopted to verify that the precipitates have the same composition and structure. Theoretical-ly, Hillert and Staffansson's regular model about stoichimetric phase was used to describe the thermodynamic proper-ties of multi-component precipitate. Calculated results agree well with experimental values from literatures.

关键词： equilibrium niobium precipitate, austenite

Calculation Models of Mass Action Concentrations for Metallic Melts Involving Monotectic

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Journal of university of science and technology Beijing 2001年第4期8卷 248-253页

作者： Jian Zhang Metallurgy school, university of science and {3. Beijing, Beijing 100083. china Univ Sci & Technol Beijing Met Sch Beijing 100083 Peoples R China

Based on the phase diagrams, measured activities as well asDeltaG(m) and DeltaG(xs), calculating models of mass action concentrations for metallic melts involving monotectic have been formulated. The calculated results agree with practice on the whole, showing that the models deduced generally can reflect the structural characteristics of these melts. The metastable compounds formed in the melts are of the types A(2)B(3., AB(2), A(2)B(3. or AB and A(2)B(3.+AB etc..

关键词： metallic melts monotectic activity mass action concentration

ON SPECTRUM OF NETWORKS BASED ON MATRIX OF LINK-STATE AND ITS SYMMETRY

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Journal of Systems science & Complexity 2009年第2期22卷 243-251页

作者： Liuqing XIAO Shipeng ZHOU Department of Mathematics Shanghai Jiao Tong University Shanghai 200030 China. school of Business University of Shanghai for Science and Technology Shanghai 200093 China.

This paper constructs a new spectrum of networks by means of the matrix of link-state ofthe network,which can reveal the characteristics of the correlation between the degrees of the ***,the computation of this spectrum of networks is usually more feasible and more efficient due tothe much lower order of its matrix of link-state than its adjacent matrix in *** estimatesfor the bounds of the key eigenvalues in the spectrum are obtained,the corresponding inequalities arepresented and *** the sake of its application,the authors define spectrum of networks in twoways,and all theorems are given in parallel for both kinds of *** addition,the authors finda symmetry in the spectrum,which is relative to the characteristic of structure of its network to someextent.

关键词： Complex network Laplacian matrix matrix of link-state spectrum of networks symmetry

A New Safety Electric Initiating System

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 306-308页

作者： Daze Lin(Resource Engineering school, university of science and {3. Beijing, Beijing 100083. china) Univ of science and technology Beijing Beijing China

Based on the analysis of weakness on the safety of traditional electric detonators, a BJ-l safety electric detonator initiatingsystem and its corresponding safe examination technique were successfully developed. By leading false foot wires and taking advantageof the transmitting frequency band of Mo-Zn ferrite, detonators in this new system can completely impede the direct induction of outsidecrosstalk that may cause casual firing in the ordinary as well as eleclromagnetic ones. Possible causality by lightning was discussed. Results are presented, of its safety tests on resistance to direct and alternating current, electrostatic, and crosstalk induced by damp leakagein saturated salty water.

关键词： electric detonator blasting engineering, electric initiating system, safety