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Effects of building aspect ratio,diurnal heating scenario,and wind speed on reactive pollutant dispersion in urban street canyons

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Journal of Environmental Sciences 2012年第12期24卷 2091-2103页

作者： Nelson y.O.Tong Dennis y.C.Leung Department of Mechanical Engineering The University of Hong Kong

A photochemistry coupled computational fluid dynamics （CFD） based numerical model has been developed to model the reactive pollutant dispersion within urban street canyons, particularly integrating the interrelationship among diurnal heating scenario （solar radiation affections in nighttime, daytime, and sun-rise/set）, wind speed, building aspect ratio （building-height-to-street-width）, and dispersion of reactive gases, specifically nitric oxide （NO）, nitrogen dioxide （NO2） and ozone （O3） such that a higher standard of air quality in metropolitan cities can be achieved. Validation has been done with both experimental and numerical results on flow and temperature fields in a street canyon with bottom heating, which justifies the accuracy of the current model. The model was applied to idealized street canyons of different aspect ratios from 0.5 to 8 with two different ambient wind speeds under different diurnal heating scenarios to estimate the influences of different aforementioned parameters on the chemical evolution of NO, NO2 and 03. Detailed analyses of vertical profiles of pollutant concentrations showed that different diurnal heating scenarios could substantially affect the reactive gases exchange between the street canyon and air aloft, followed by respective dispersion and reaction. Higher building aspect ratio and stronger ambient wind speed were revealed to be, in general, responsible for enhanced entrainment of 03 concentrations into the street canyons along windward walls under all diurnal heating scenarios. Comparatively, particular attention can be paid on the windward wall heating and nighttime uniform surface heating scenarios.

关键词： photochemistry reactive pollutant dispersion building aspect ratio diurnal heating scenario wind speed urban streetcanyon

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PURIFICATION OF COBALT ANOLyTE USING THE NOVEL SOLVENT EXTRACTION SySTEM

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Acta Metallurgica Sinica(English Letters) 2003年第2期16卷 114-121页

作者： y.F.Shen W.y.Xue W.y.Niu Jinchuan Non-ferrous Metals Complex Jinchuan 737100ChinaState Key Laboratory of Rolling and AutomationNortheastern UniversityShenyang 110014ChinaState Key Laboratory of Rolling and AutomationNortheastern UniversityShenyang 110014ChinaState Key Laboratory of Rolling and AutomationNortheastern UniversityShenyang 110014China

In present research, a novel extractant system (D2EHPA + naphthenic acid + pyridine- ester) was used to purify cobalt anolyte and a simulated industrial production were carried out. This novel extraction system can extract Cu and/or Ni against Co from chloride medium solutions at pH range of 2.5-4.5. About 2g/l nickel and 0.2g/l copper were removed from the cobalt chloride anolyte containing about 100g/l cobalt and 200g/l chloride ions respectively, the raffinate contains nickel and copper less than 0.03g/l and 0.0003g/l respectively and can be used to electrolyze high-purity cobalt. About 5.5t cobalt anolyte was purified in the simulation industrial experiment and kilogram quantities of cobalt of 99.98% purity and about 95% recovery have been produced.

关键词： solvent extraction nickel cobalt anolyte naphthenic acid pyridine-ester

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Effect of site amplification on inelastic seismic response

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Earthquake Engineering and Engineering Vibration 2019年第3期18卷 535-554页

作者： Adhikary S Singh y Department of Civil Engineering Visvesvaraya National Institute of Technology Nagpur-440010 Maharashtra India Department of Earthquake Engineering Indian Institute of Technology Roorkee-247667 Uttarakhand India

The available models for eff ective periods of site and structure are reviewed in context of frequency tuning in the inelastic seismic response of soil-structure system. The eff ect of seismic intensity and ductility demand, on the eff ective periods, is investigated, and inelastic site amplifi cation is shown to be strongly correlated to the normalized eff ective period. Two non-dimensional parameters, analogous to the conventional site amplifi cation factors in codes, are defi ned to quantify the inelastic site amplifi cation. It is shown that the inelastic site amplifi cation factor (i.e. ratio of constant ductility spectral ordinates at soil site to those at rock outcrop) is able to represent the site eff ects more clearly, as compared to the inelastic site amplifi cation ratio (i.e. ratio of inelastic spectral ordinates at soil site to the corresponding elastic spectral ordinates at rock outcrop). Further, the peak in the amplifi cation factor corresponding to the eff ective site period diminishes rapidly with increasing ductility demand.

关键词： site amplifi cation normalized response spectra eff ective period inelastic seismic response inelastic site amplifi cation factor

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Mathematical modelling of axonal microtubule bundles under dynamic torsion

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 829-844页

作者： J.y.WU Hong yUAN L.y.LI MOE Key Laboratory of Disaster Forecast and Control in Engineering Institute of Applied MechanicsJinan University School of Engineering University of Plymouth

Owing to its viscoelastic nature, axon exhibits a stress rate-dependent me- chanical behavior. An extended tension-shear chain model with Kelvin-Voigt viscoelas- ticity is developed to illustrate the micromechanical behavior of the axon under dynamic torsional conditions. Theoretical closed-form expressions are derived to predict the de- formation, stress transfer, and failure mechanism between microtubule （MT） and tau protein while the axon is sheared dynamically. The results obtained from the present an- alytical solutions demonstrate how the MT-tau interface length, spacing between the tau proteins, and loading rate affect the mechanical properties of axon. Moreover, it is found that the MTs are more prone to rupture due to the contributions from the viscoelastic effects. Under the torsional force, the MTs are so long that the stress concentrates at the loaded end where axonal MTs will break. This MT-tau protein dynamics model can help to understand the underlying pathology and molecular mechanisms of axonal injury. Additionally, the emphasis of this paper is on the micromechanical behavior of axon, whereas this theoretical model can be equally applicable to other soft or hard tissues, owning the similar fibrous structure.

关键词： torsion biocomposite diffuse axonal injury (DAI) Kelvin-Voigt viscoelas-tic model dynamic response tension-shear chain model

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Interaction of Nicotine and Bovine Serum Albumin

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Chinese Chemical Letters 2000年第3期11卷 247-250页

作者： Wang, y Cheng, y Sun, HF Peking Univ Dept Tech Phys Div Appl Chem Beijing 100871 Peoples R China

The binding of nicotine to bovine serum albumin (BSA) was studied by UV absorption. fluorescence, and H-1 NMR methods. With the addition of nicotine, the absorption band of BSA at about 210 nm decreased gradually, moved to longer wavelengths, and narrowed. BSA fluorescence of tryptophan residue was quenched by nicotine. The H-1 NMR peaks of nicotine moved to downfield by the addition of BSA. The experimental results showed that nicotine was capable of binding with BSA to form a 1:1 complex. BSA's high selectivity for nicotine binding suggests a unique role for this protein in the detoxification and/or transport of nicotine.

关键词： nicotine BSA UV absorption fluorescence H-1 NMR

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A COMPREHENSIVE MODEL OF LASER CLADDING By POWDER FEEDING

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 21-27页

作者： y.L.Huang G.y.Liang J.y.Su School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaSchool of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaSchool of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

A novel model was presented to predict the evolutionary development of cladding layer, and a method based on Lambert-Beer theorem and Mie's theory was adopted to treat the interaction between powder stream and laser beam. By using the continuum model and enthalpy-porosity method, the fluid flow and heat transfer in solid-liquid phase change system were simulated. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. Numerical computation was performed for Stellite 6 cladding on steel, the obtained results are coincident with those measured in experiment basically.

关键词： laser cladding powder feeding cladding layer interaction

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Study of Physicochemical Properties and Active Oxygen in Structures ofLayered Mixed La_(4)BaCu_(5-x)MxO_(13+λ)(M=Mn,Co)

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Journal of Rare Earths 1999年第2期17卷 52-56页

作者： Liu, y yang, XG Wu, y Chinese Acad Sci Changchun Inst Appl Chem Changchun 130022 Peoples R China

Two series of layered mixed oxides La4BaCu5-xMxO13+(M=Mn, Co, x=05) were prepared and characterized by means of XRD, XPS, O2TPD and chemical analysis. The results show that their structures are 5layered ABO3 perovskite, and the XPS and O2TPD investigation confirms that there exists synergistic effect between Cu ion and M when M ion is doped into the lattice of La4BaCu5O13+, and the synergistic effect between Mn and Cu is stronger than that of CuCo.

关键词： Rare earths Layered mixed oxides Synergistic effect Active oxygen species

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QUASI-INTERPOLATING OPERATORS AND THEIR APPLICATIONS IN HyPERSINGULAR INTEGRALS

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Journal of Computational Mathematics 1998年第4期16卷 337-344页

作者： Wong, RH Lu, y Dalian Univ Technol Inst Math Sci Dalian 116024 Peoples R China

The purpose of this paper is to propose and study a class of quasi-interpolating operators in multivariate spline space S-1/2(Delta(mn)(2*)) on non-uniform type-2 triangulation. Based on the operators, we construct cubature formula for two-dimensional hypersingular integrals. Some computing work have been done and the results are quite satisfactory.

关键词： hypersingular integral finite-part integral quasi-interpolating operator non-uniform type-2 triangulation

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Structural and Optical Properties and Emerging Applications of Metal Nanomaterials

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Journal of Materials Science & Technology 2008年第4期24卷 433-446页

作者： Tammg y.Olson Department of Chemistry and Biochemistry University of CaliforniaSanta CruzCA 95064USA

Nanomaterials possess intriguing optical properties that depend sensitively on size, shape, and material content of the structures. Controlling such structural characteristics of the nanostructures allows the tailoring of their physical and chemical properties, e.g. optical, electronic, and catalytic, to achieve what is desired lot specific applications of interest. This review will cover the development of various shapes for silver and gold nanomaterials with emphasis on their relation to optical properties. Examples of various modern synthetic methods and characterization techniques are highlighted. The influence of the metal nanomaterial＇s shape and optical absorption on surface enhanced Raman scattering （SERS） and a final note on new emerging applications of metal nanostructures are also discussed.

关键词： Nanomaterial Metal nanostructure Optical properties Size and shape effect

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EVOLUTION OF SINGLE ELLIPTIC VORTEX RINGS

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Acta Mechanica Sinica 1997年第1期13卷 17-25页

作者： Zhao, y Shi, XG Department of Mechanics and Engineering Science Peking University The State Key Laboratory for Turbulence Research Beijing China

The evolution of single elliptic vortex rings for initial aspect ratio (AR) = 2,4,6 has been studied. The incompressible Navier-Stokes equations are solved by a dealiased pseudo-spectral method with 64(3) grid points in a periodic cube. We find that there are three kinds of vortex motion as AR increases and bifurcation occurs at certain AR. The processes of advection, interaction and decay of vortex ring are discussed. Numerical results coincide with experiments and other authors' numerical simulation.

关键词： elliptic vortex ring pseudo-spectral method bifurcation vortex reconnection

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