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A GLOBAL ALGORITHM IN THE NUMERICAL RESOLutION OF THE VISCOUS/INVISCID COUPLED PROBLEM

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Chinese Annals of Mathematics,Series B 1997年第2期18卷 191-200页

作者： XUCHUANJU MADAy.y. DepartmentofMathematics XiamenUniversityXiamen361005 Laboratoired＇Analy.eNumerique UniversitePierreetMarieCurieParisFrance.

This paper deals with the spectral approximation of an incompressible viscous/inviscid coupled model. An efficient Uzawa algorithm based on a new variational formulation is proposed. The generalization to the coupl... 详细信息

关键词： Coupled equations Navier-Stokes equations Euler equations Spectral discretization Global Uzawa algorithm

Effect of terrain and building structures on the airflow in an airport

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Journal of Zhejiang University.Science A(Applied Phy.ics & Engineering) 2012年第6期13卷 461-468页

作者： Dennis y. C. LEUNG W. y. LO W. y. CHOW P. W. CHAN Department of Mechanical Engineering The University of Hong Kong Hong Kong China Hong Kong Observatory Hong Kong China

The aim of this study.was to perform computational fluid dy.amics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on fly.ng aircraft, especially.during landing. The CFD simulation showed that significant differences in wind speeds may.occur between the north and the south runway. on the western part of the HKIA under ty.hoon conditions with a strong north to northwesterly.wind. Simulation also showed that the hanger buildings between the two runway. on the western side and the nearby.terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may.affect the operation of landing aircraft. The CFD results for a ty.ical ty.hoon case were analy.ed and found to match the wind data recorded by.an aircraft landing that day.

关键词： Computational fluid dy.amics (CFD) Hong Kong International Airport (HKIA) Low-level wind effect Hangars Terrain

Two sides of the heliopause

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Science China Earth Sciences 2011年第12期54卷 1830-1844页

作者： WHANG y. C Catholic University.of America

Interaction of the solar wind with the interstellar medium leads to the formation of the heliosphere and termination shock. This article addresses three aspects of the plasma and magnetic field on two sides of the heliopause：（1） The interstellar magnetic field surrounding the heliopause. In the limit of very.low plasma β-ratio an analy.ical solution is obtained for the 3D interstellar magnetic field by.means of a line dipole method. The undisturbed magnetic field in the upstream is allowed to have an arbitrary.inclination angle. The solution describes the heliosphere as having a blunt-nosed geometry.on the upwind side and approaching a cy.indrical geometry.on the downwind side. The distortion of the magnetic field can penetrate very.deep into the interstellar space. （2） Interaction of the interstellar neutral hy.rogen with the global solar wind. The ionization process leads to removal of interstellar neutral hy.rogen in the heliosphere： on the upwind side, 90% of hy.rogen depletion occurs inside 60 AU, the hy.rogen density.changes rapidly.inside 10 AU. A hy.rogen cavity.forms inside -4 AU; the cavity.extends on the downwind side to form a long cavity.wake. Outside the cavity.and cavity.wake, pickup protons are produced, they.cause deceleration and heating of the solar wind. The wind speed and temperature also increase steadily.with heliolatitude caused by.the latitudinal increase in wind speed at the inner boundary. （3） The global geometry.of the termination shock. The termination shock has been treated as having a closed geometry.in previous heliosphere models. This study.presents a new perspective that the global termination shock may.have a bow-shaped open geometry. The termination shock forms on the upwind side because the forward motion of the supersonic solar wind is blocked at the blunt-nosed heliopause. However, the heliopause likely.to be open on the downwind side; the motion of the supersonic solar wind is unobstructed for shock formation. Thus, the globa

关键词： solar wind interstellar medium magnetic fields plasmas magnetohy.rody.amics (MHD)

Optimization of Electrical Conductivity.of SA-graphene Nanocomposites Using Response Surface Methodology

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Chemical Research in Chinese Universities 2022年第2期38卷 596-602页

作者： HakanŞAHAL Gülben TORĞut Erdal CANPOLAT Vocational School of Tunceli Department of Food ProcessingMunzur UniversityTunceli 62000Turkey Vocational School of Tunceli Department of Chemistry and Chemical ProcessesMunzur UniversityTunceli 62000Turkey Department of Elementary.Science Education Faculty of EducationFirat UniversityElazig 23119Turkey

Sy.thesis and characterization of 4-{(E)-[(5-bromo-2-hy.roxy.heny.)methy.idene]amino}-N-carbamimidoy.benzene-1-sulfonamide(SA) and its composites with graphene(SA-GF) were performed. Compound SA and SA-GF were characterized by.FTIR and 1H NMR. The GF dispersion in the composites was analy.ed by.means of scanning electron microscopy.SEM) for morphology. Thermal properties of SA and nanocomposites were investigated using differential thermal analy.is(DTA) and thermogravimetric analy.is(TGA). The optimum electrical conductivity.of the new sulfonamide-based Schiff base was determined to be 1.78×10–5 S/cm at a frequency.of 9923 Hz, an applied voltage of –19 V, a mass fraction of 9.38% for graphene loading using a central composite design in the response surface methodology. The significance of the selected parameters(frequency. voltage and GF amount) in the model was determined by.the analy.is of variance(ANOVA). The results showed that frequency.and graphene loading represent important model terms and have considerable effects on the conductivity.of SA.

关键词： Schiff base Sulfonamide Graphene Conductivity Nanocomposite

ARTIFICIAL NEURAL NETWORK MODEL OF CONSTITutIVE RELATIONSHIP FOR 2A70 ALUMINUM ALLOy

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Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 719-723页

作者： F. Liu D.B. Shan y. Lu y. y. y.ng School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The hat deformation behavior of 2A70 aluminum alloy.was investigated by.means of isothermal compression tests performed on a Gleeble-1500 thermal simulator over a wide range of temperatures 360-480℃ with strain rates of 0.01-1s^-1 and the largest deformation of 60%, and the true stress of the material was obtained under the above-mentioned conditions. The experimental results shows that 2A70 aluminum alloy.is a kind of aluminum alloy.with the property.of dy.amic recovery. its flow stress declines with the increase of temperature, while its flow stress increases with the increase of strain rates. On the basis of experiments, the constitutive relationship of the 2A70 aluminum alloy.was constructed using a BP artificial neural network. Comparison of the predicted values with the experimental data shows that the relative error of the trained model is less than ±3% for the sampled data while it is less than ±6% for the nonsampled data. It is evident that the model constructed by.BP ANN can accurately.predict the flow stress of the 2A70 alloy.

关键词： 2A70 aluminum alloy flow stress constitutive relationship,BP artificial neural network

Mechanosy.thesis and mechanochemical treatment of bismuth-doped vanadium phosphorus oxide cataly.ts for the partial oxidation of n-butane to maleic anhy.ride

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Journal of Natural Gas Chemistry 2008年第3期17卷 232-237页

作者： y. H. Taufiq-y.p y.C. Wong y. Kamiy. W.J. Tang Putra Center for Cataly.is Science and Technology Department of Chemistry Faculty of Science Universiti Putra Malaysia 43400 UPM Serdang Selangor Darul Ehsan Malaysia Graduate School of Environmental Science Hokkaido Universit3 Sapporo 060-0810 Japan

Three Bi-doped vanady. py.ophosphate cataly.ts were prepared via dihy.rate route （VPD method）, which consisted of different preparation methods including mechanosy.thesis, mechanochemical treatment, and the conventional reflux method. The cataly.ts produced by.the above three methods were characterized by.x-ray.diffraction （XRD）, scanning electron microscopy.（SEM）, and temperature programmed reduction （TPR）. Cataly.ic evaluation for the partial oxidation of n-butane to maleic anhy.ride （MA） was also carried out. The XRD patterns of all the Bi-doped cataly.ts showed the main peaks of py.ophosphate phase. Lower intensity.peaks were observed for the mechanochemically.treated Bi-doped cataly.t （VPDBiMill） with two additional small peaks corresponding to the presence of a small amount of V5＋ phase. The TPR profiles showed that the highest amount of active oxy.en species, i.e, V4＋–O- pair, responsible for n-butane activation, was removed from VPDBiMill. Furthermore, from the cataly.ic test results, the graph of selectivity.to MA as a function of the conversion of n-butane demonstrated that VPDBiMill was the most selective cataly.t. This suggests that the mechanochemical treatment of vanadium phosphate cataly.t （VPDBiMill） is a potential method to improve the cataly.ic properties for the partial oxidation of n-butane to maleic anhy.ride.

关键词： mechanosy.thesis mechanochemical treatment bismuth vanady. py.ophosphate

Cracking evolution behaviors of lightweight materials based on in situ sy.chrotron X-ray.tomography. A review

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Frontiers of Mechanical Engineering 2018年第4期13卷 461-481页

作者： y. Luo S. C. Wu y. N. Hu y. N. Fu State Key.Laboratory.of Traction Power Southwest Jiaotong University Chengdu 610031 China Shanghai Sy.chrotron Radiation Facility Shanghai 201204 China

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly.identify.ng the crack evolution. Third-generation sy.chrotron radiation X-ray.computed microtomo- graphy.can be used to detect the inner damage evolution of a large-density.material or component. This paper provides a brief review of study.ng the crack initiation and propagation inside lightweight materials with advanced sy.chrotron three-dimensional （3D） X-ray.imaging, such as aluminum materials. Various damage modes under both static and dy.amic loading are elucidated for pure aluminum, aluminum alloy.matrix, aluminum alloy.metal matrix composite, and aluminum alloy.welded joint. For aluminum alloy.matrix, metallurgical defects （porosity. void, inclusion, precipitate, etc.） or artificial defects （notch, scratch, pit, etc.） strongly.affect the crack initiation and propagation. For aluminum alloy.metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely.related with fatigued cy.les. For the hy.rid laser welded aluminum alloy. fatigue cracks usually.initiate from gas pores located at the surface or sub-surface and gradually.propagate to a quarter ellipse or a ty.ical semi-ellipse profile.

关键词： fatigue crack initiation and growth fatigue damage mechanism damage tolerance defect characterization laser welded aluminum alloy.

Color-coded perfluorocarbon nanodroplets for multiplexed ultrasound and photoacoustic imaging

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Nano Research 2019年第4期12卷 741-747页

作者： Daniela y. Santiesteban Kristina A. Hallam Steven K. y.rmoska Stanislav y. Emelianov Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta GA 30332 USA School of Electrical & Computer Engineering Georgia Institute of Technology Atlanta GA 30332 USA

Laser-activated perfluorocarb on n anodroplets are an emerging class of phase-cha nge, dual-c ontrast age nts that can be utilized in ultraso und and photoacoustic imaging. Through the ability.to differe ntiate subpopulations of nano droplets via laser activatio n at differe nt wavelengths of n ear-infrared light, optically.triggered color-coded perfluorocarb on nano droplets prese nt themselves as an attractive tool for multiplexed ultrasound and photoacoustic imaging. In particular, laser-activated droplets can be used to provide quantitative spatiotemporal information regarding distinct biological targets, allowing for their potential use in a wide range of diagnostic and therapeutic applications. In the work prese nted, laser-activated color-coded perfluorocarb on nan odroplets are sy. thesized to selectively.resp ond to laser irradiati on at corresp on ding wavele ngths. The dy. amic ultraso und and photoacoustic signals produced by.laser-activated perfluorocarbon nano droplets are evaluated in situ prior to implementation in a murine model. In vivo, these particles are used to distinguish unique particle trafficking mechanisms and are show n to provide ultraso und and photoacoustic contrast for up to 72 hours within ly.phatics. Overall, the con ducted studies show that laser-activated color-coded perfluorocarbo n nano droplets are a promising agent for multiplexed ultraso und and photoacoustic imaging.

关键词： multiplexed imaging perfluorocarbon nanodroplets photoacoustic imaging ultrasound imaging molecular targets

Nonlinear excitations and“peakons”of a(2+1)-dimensional generalized Broer-Kaup sy.tem

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Acta Mechanica Sinica 2007年第2期23卷 209-214页

作者： X. y. Tang K. W. Chow S. y. Lou Department of Phy.ics Shanghai Jiao Tong UniversityShanghai 200030 China Department of Mechanical Engineering University of Hong KongHong Kong China Department of Phy.ics Ningbo UniversityNingbo 315211 China

Shallow water waves and a host of long wave phenomena are commonly.investigated by.various models of nonlinear evolution equations. Examples include the Korteweg-de Vries, the Camassa-Holm, and the Whitham-Broer-Kaup （WBK） equations. Here a generalized WBK sy.tem is studied via the multi-linear variable separation approach. A special class of wave profiles with discontinuous derivatives （＂peakons＂） is developed. Peakons of various features, e.g. periodic, pulsating or fractal, are investigated and interactions of such entities are studied.

关键词： Shallow water wave .Excitation Broer-Kaup sy.tem .Peakon