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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)

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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

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Electromechanical modeling and experimental analy.is of a compression-based piezoelectric vibration energy.harvester

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International Journal of Smart and Nano Materials 2014年第3期5卷 152-168页

作者： X.Z.Jiang y.c Li J.Wang J.c.Li centre for Built Infrastructure Research Faculty of Engineering and Information TechnologyUniversity of Technology SydneyPO Box 12315 BroadwayUltimoNSW 2007Australia School of Mechanical Engineering Nanjing University of Science&Technology200 Xiaolingwei StreetXuanwu DistrictNanjing 210094China

Over the past few decades,wireless sensor networks have been widely.used in the field of structure health monitoring of civil,mechanical,and aerospace ***,most wireless sensor networks are battery.powered and it is costly.and unsustainable for maintenance because of the requirement for frequent battery.*** an attempt to address such issue,this article theoretically.and experimentally.studies a compression-based piezoelectric energy.harvester using a multilay.r stack configuration,which is suitable for civil infrastructure sy.tem applications where large compressive loads occur,such as heavily.vehicular loading acting on *** this article,we firstly.present analy.ical and numerical modeling of the piezoelectric multilay.r stack under axial compressive loading,which is based on the linear theory.of piezoelectricity.A two-degree-of-freedom electromechanical model,considering both the mechanical and electrical aspects of the proposed harvester,was developed to characterize the harvested electrical power under the external electrical *** closed-form expressions of the electromechanical models have been derived to analy.e the mechanical and electrical properties of the proposed *** theoretical analy.es are validated through several experiments for a test prototy.e under harmonic *** test results exhibit very.good agreement with the analy.ical analy.es and numerical simulations for a range of resistive loads and input excitation levels.

关键词： vibration energy.harvesting piezoelectric 2-DOF electromechanical model large-force low-frequency

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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

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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.

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current Status in Lay.red Ternary.carbide Ti_3Sic_2,a Review

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Journal of Materials Science & Technology 2009年第1期25卷 1-38页

作者： H.B. Zhang y.W. Bao y. c. Zhou Sheny.ng National Laboratory.for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

This article provides a review of current research activities that concentrate on Ti3Sic2. We begin with an overview of the cry.tal and electronic structures, which are the basis to understand this material. Followings are the sy.thetic strategies that have been exploited to achieve, and the formation mechanism of Ti3Sic2. Then we devote much attentions to the mechanical properties and oxidation/hot corrosion behaviors of Ti3Sic2 as well as some advances achieved recently. At the end of this paper, we elaborate on some new discoveries in the Ti3Sic2 sy.tem, and also give a brief discussion focused on the ＂microstructure -property. relationship.

关键词： Lay.red ternary.ceramics Ti3Sic2 Mechanical properties Oxidation

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Design and analy.is of Salisbury.screens and Jaumann absorbers for solar radiation absorption

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Frontiers in Energy 2018年第1期12卷 158-168页

作者： Xing FANG c. y. ZHAO Hua BAO Institute of Engineering Thermophy.ics Shanghai Jiao Tong UniversityShanghai 200240 China University.of Michigan-Shanghai Jiao Tong University.Joint Institute Shanghai Jiao Tong University Shanghai 200240 China

Two ty.es of resonance absorbers, i.e., Salis- bury.screens and Jaumann absorbers are sy.tematically.investigated in solar radiation absorption. Salisbury.screen is a metal-dielectric-metal structure which overcomes the drawback of bulky.thickness for solar spectrum. Such structures have a good spectral selective absorption property. which is also insensitive to incident angles and polarizations. To further broaden absorption bandwidth, more metal and dielectric films are taken in the structure to form Jaumann absorbers. To design optimized structural parameters, the admittance matching equations have been derived in this paper to give good initial structures, which are valuable for the following optimization. Moreover, the analy.is of admittance loci has been conducted to directly.show the effect of each lay.r on the spectral absorptivity. and then the effect of thin films is well understood. Since the fabrication of these lay.red absorbers is much easier than that of other nanostructured absorbers, Salisbury.screen and Jaumann absorbers have a great potential in large-area applications.

关键词： thin films admittance loci solar absorber

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Numerical Modeling and Analy.is of Grooved Surface Applied to Film cooling

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Journal of Bionic Engineering 2011年第4期8卷 464-473页

作者： L. Guo Z. c. Liu y. y. y.n Z. W. Han Faculty.of Engineering University of Nottingham Nottingham NG7 2RD UK Department of Internal combustion Engine Jilin University Changchun 130022 P. R. China Key.Laboratory.of Bionic Engineering （Ministry.of Education China） Jilin University Changchun 130022 P. R. China

In order to improve the efficiency.of film cooling, numerical investigation was carried out to study.the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were concerned. The modeling was per- formed using Fluent software with the adoption of Shear-Stress Transport （SST） k-ωmodel as the turbulence closure. The coolant was supplied by.a single film cooling hole with an inclination angle of 30°. The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6, respectively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerody.amic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented. The numerical results were validated using experimental data extracted from a benchmark test. Good agreements between numerical results and the ex- perimental data were observed. For the film cooling efficiency. it shows that both local and laterally.averaged cooling effectiveness can be improved by.the non-smooth surface at different blowing ratios. Using the grooved surface, the turbulence intensity.upon the plate can be reduced notably. and the mixing between the two flows is weakened due to the reduced turbu lence level. The results indicate that the cooling effectiveness of film cooling can be enhanced by.apply.ng the grooved surface.

关键词： film cooling non-smooth surface cooling effectiveness grooved structure blowing ratio

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BEM Analy.is of Wave Propagation in a Water-Filled Borehole in an Anisotropic Solid

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Tsinghua Science and Technology 2007年第5期12卷 520-526页

作者： S. Hirose y. Ushida c. y. Wang Department of Mechanical and Environmental Engineering Tokyo Institute of Technology Tokyo 152-8552 Japan Schlumberger-Doll Research 36 Old Quarry Road Ridgefield CT 06877-4108 USA

This paper describes a time-domain boundary.element method developed to analy.e the interactions of acoustic and elastic waves near the interfaces between water and an anisotropic elastic solid. Two models are analy.ed with one being the interface between two half spaces of fluid and solid and the other being a fluid region sandwiched by.half space domains of anisotropic elastic solids. Both monopole and dipole point sources are used to generate an initial pressure wave in the fluid. Some snapshots of the transient wave behavior near the fluid-solid interfaces are given. The effect of the anisotropy.in the solid on the pressure waveforms in the fluid is discussed. The numerical results allow detailed arrival identification and interpretation of acoustic and elastic waves propagating along the fluid-solid interfaces.

关键词： boundary.element method wave propagation anisotropic solid fluid-solid interface

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Residual finiteness of outer automorphism groups of certain 1-relator groups

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Science china Mathematics 2009年第2期52卷 287-292页

作者： KIM Goansu TANG c. y. y.ungnam University University.of Waterloo Waterloo

We prove that certain 1-relator groups have Property.E. Using this fact, we characterize all conjugacy.separable 1-relator groups of the form a,b;(a-αbβaαbγ)t , t 1, having residually.finite outer automorphism gro... 详细信息

关键词： outer automorphism groups 1-relator groups residually.finite conjugacy.separable 20E26 20E06 20F28

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