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APPLICATION OF A NOVEL ALgORITHM FOR MOVINg SURFACE FLOWS

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Journal of Hydrodynamics 1997年第1期9卷 87-95页

作者： Xu wei-xing, g. D. Raithby, g. D. StubleyDepartment of Mechanical Engineering, University of Waterloo, Waterloo, Ontario, CanadaN2L3g1 Univ of Waterloo Waterloo Canada

Purpose:To demonstrate a novel algorithm for simulating moving surface flows. Methods: A fully conservative control volume method, on an adaptive Eulerian grid, has been developed to guarantee that the 'kinematic free surface condition 'is automatically satisfied by solving the mass and momentum conservation equations. No separate free surface tracing equation is needed. The basic idea has been extended to solve general moving surface problems by adding 'boundary-node-constraints' to the solution equation set. Results; Two application problems, a critical free surface flow over an obstruction and flow past a 2-D inflated building, were predicted by the proposed method. The predicted results were in good agreement with the corresponding experimental findings. Conclusions: The proposed moving surface model permits prescribed moving walls, free surfaces, and compliant surfaces to be simulated by the same computer code. The moving surface shape is obtained as part of the solution of the conservation equations; no surface-tracing step is needed.

关键词： CFD simulation moving surface flows algorithm

Three－Dimensional　Numerical　Simulation　of　Natural　Convection　Heat　Transfer　in　an　Inclined　Cylindrical　Annulus

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Journal of Thermal Science 1996年第3期5卷 175-183页

作者： J.g. wei W.Q. Tao (School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China) School of Energy and Power Engineering Xi’an Jiaotong University Xi’san China

A numerical study of natural convection heat transfer in an inclined cylindrical annulus has been conducted. The inner cylinder of the annulus is maintained at uniform heat flux and the outer cylinder at constant temperature. The two end walls are assumed to be insulated. A numerical code has been developed to calculate the steady state three-dimensional natural convection in an inclined cylindrical annulus, and the research emphasis is placed on the influences of inclination angle or and modified Rayleigh number Ra on the natural convection heat transfer in the annulus. Computations were carried out in the ranges of 0°α 90*, 2.5×105 Ra* and Pr=0.7 with fixed aspect ratio of H=28.97 and radius ratio of K= 3.33. The numerical results are compared with the experimental correlations from the literature and the inclination angle effect on heat transfer is found to be insignificant. Detailed results of heat transfer rate, temperature, and velocity fields are presented for the case of or α=45° and discussion is also made concerning the comparison between the numerical and experimental results for the specific case of α=90°.

关键词： enclosure flows natural convection numerical methods

Numerical and Experimental Studies of Substrate Melting and Resolidification during Thermal Spraying

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Journal of Materials Science & Technology 2003年第Z1期19卷 137-140页

作者： H.Zhang g.wei L.Zheng L.Li X.Y.Wang A.Vaidya Department of Mechanical Engineering State University of New York at Stony BrookStony BrookNY 11794USA Department of Materials Science and Engineering State University of New York at Stony BrookStony BrookNY 11794USA

A good understanding of melting and resolidification of the substrate will help us to achieve better *** model is developed to investigate the solidification of the droplet,and melting and resolidification of *** molybdenum powder spraying onto three different substrates:a stainless steel,brass(70%Cu)andaluminum by atmospheric plasma spraying has been *** maximum melting depth of the substrate hasbeen measured and compared with the numerical *** results show that the material propertiesof the splat and substrate and melting temperature of the substrate play the important roles on substrate melting.A dimensionless parameter,temperature factor,has been proposed and served as an indicator for substrate melting.

关键词： Thermal spraying Coating Melting Solidification Materials processing

Dynamic Impact of High-Density Aluminum Foam

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Acta Mechanica Solida Sinica 2022年第2期35卷 198-214页

作者： Q.Peng J.Xie H.S.Ma X.Ling X.Liu Y.g.wei LNM Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China School of Engineering and Technology China University of GeosciencesBeijing 100083China College of Engineering Peking UniversityBeijing 100871China

High-density aluminum foam can provide higher stiffness and absorb more energy during the impact Obtaining the constitutive law of such foam requires tri-axial tests with very high pressure,where difficulty may arise because the hydrostatic pressure can reach more than 30 *** this paper,instead of using tri-axial tests,we proposed three easier tests-tension,compression and shear to obtain the parameters of constitutive model(the Deshpande-Fleck model).To verify the constitutive model both statically and dynamically,we carried out addi-tional triaxial tests and direct impact tests,*** on the derived model,we performed finite element simulation to study the impact response of the present *** dimensional analysis,we proposed an empirical equation for a non-dimensional impact time the impact time divided by the time required for plastic wave travelling from the impact surface to the bottom surface,to det ermine the deformation charac teristic of the aluminum foam after *** the case with t_(d)≤1,the deformation tends to exhibit a shock-type characteristic,while for the case with t_(d)>5,the deformation tends to exhibit an upsetting-type characteristic.

关键词： High density aluminum Foam Deshpande-Fleck model Finite element method Impact analysis Plastic wave

Regional differences in crustal structure of the North China Craton from receiver functions

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Science China Earth Sciences 2015年第10期58卷 2200-2210页

作者： wei Zigen CHU RiSheng CHEN Ling State Key Laboratory of geodesy and Earth's Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

Moho depth and crustal average Poisson＇s ratio for 823 stations are obtained by H-n： stacking of receiver functions. These, to- gether with topography and receiver function amplitude information, were used to study the crustal structure beneath the North China Craton （NCC）. The results suggest that modified and preserved crust coexist beneath the craton with generally Airy-type isostatic equilibrium. The equilibrium is relatively low in the eastern NCC and some local areas in the central and western NCC, which correlates well with regional geology and tectonic features. Major differences in the crust were observed beneath the eastern, central, and western NCC, with average Moho depths of 33, 37, and 42 km and average Poisson＇s ratios of 0.268, 0.267 and 0.264, respectively. Abnormal Moho depths and Poisson＇s ratios are mainly present in the rift zones, the northern and southern edges of the central NCC, and tectonic boundaries. The crust beneath Ordos retains the characteristics of typical craton. Poisson＇s ratio increases roughly linearly as Moho depth decreases in all three parts of the NCC with different slopes. Receiver function amplitudes are relatively large in the northern edge of the eastern and central NCC, and small in and near the rifts. The Yanshan Mountains and southern part of the Shanxi rift show small-scale variations in the receiver-function ampli- tudes. These observations suggest that overall modification and thinning in the crust occurred in the eastern NCC, and local crustal modification occurred in the central and westem NCC. Different crustal structures in the eastern, central, and western NCC suggest different modification processes and mechanisms. The overall destruction of the crustal structure in the eastern NCC is probably due to the westward subduction of the Pacific Plate during the Meso-Cenozoic time; the local modifications of the crust in the central and western NCC may be due to repeated reactivations at zones with a heterogeneous s

关键词： North China Craton Moho depth Poisson's ratio gravitational equilibrium receiver function amplitude regional difference in crust

A low-frequency and broadband wave-insulating vibration isolator based on plate-shaped metastructures

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1171-1188页

作者： wei wei Feng gUAN Xin FANg College of Intelligent Science National University of Defense TechnologyChangsha410073China Naval Research Academy Beijing100161China

A metamaterial vibration isolator,termed as wave-insulating isolator,is proposed,which preserves enough load-bearing capability and offers ultra-low and broad bandgaps for greatly enhanced wave *** consists of plate-shaped metacells,whose symmetric and antisymmetric local resonant modes offer several low and broad mode bandgaps although the complete bandgap remains high and *** bandgap mechanisms,vibration isolation properties,effects of key parameters,and robustness to complex conditions are *** experimentally demonstrated,the wave-insulating isolator can improve the vibration insulation in the ranges of[50 Hz,180 Hz]and[260 Hz,400 Hz]by 15 dB and 25 dB,respectively,in contrast to the conventional isolator with the same first resonant frequency.

关键词： metamaterial and metastructure vibration isolation bandgap wave insulation plate

Planet wind: Planetary evolution dominated by electromagnetic forces

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Science China Earth Sciences 2024年第10期67卷 3331-3336页

作者： Yong wei Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

1. Introduction Over the five centuries since Copernicus, the focus of planetary science has transitioned from the visible realm to the invisible. In the more than 60 years following the advent of the space age, our a... 详细信息

关键词： evolution dominated planetary

The lithology and composition of lunar mantle modified by ilmenite bearing cumulate:A thermodynamic model

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Acta geochimica 2024年第5期43卷 856-875页

作者： wei Huang wei Du State Key Laboratory of Ore Deposit geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of Sciences Beijing 100049China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

Due to their high density,the ilmenite-bearing cumulates(IBC)(with or without KREEP)formed during the late-stage lunar magma ocean solidification are thought to sink into the underlying lunar mantle and trigger lunar mantle *** evidence implied that IBC may descend deep inside the Moon and remain as a partially molten layer at the core-mantle boundary(CMB).However,partial melting may have occurred on the mixed mantle cumulates during the sinking of IBC/KREEP and the silicate melt may be positively buoyant,thus preventing the IBC/KREEP layer from sinking to the ***,we perform thermodynamic simulation on the stability of lunar mantle cumulates at different depths mixed with different amounts of IBC/KREEP from an updated LMO *** modeling results suggest that the sinking of IBC/KREEP will cause at least 5 wt%partial melting in the shallow(~120 km)and a much larger degree of partial melting in the deep lunar mantle(~420 km).Due to the density contrast with the surrounding mantle,IBC/KREEP-bearing melts could potentially decouple under certain *** modified lunar mantle by sinking of IBC/KREEP can better explain the formation of different kinds of lunar basaltic magma than the primary lunar mantle formed through differentiation of lunar magma *** of IBC/KREEP back into the lunar mantle may introduce plagioclase,clinopyroxene,garnet,and incompatible radioactive elements into the deep lunar mantle,which will further affect the thermal and chemical evolution of the lunar interior.

关键词： Ilmenite-bearing cumulate KREEP Partial melting Lunar mantle overturn pMELTS

Task-specific Part Discovery for Fine-grained Few-shot Classification

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Machine Intelligence Research 2024年第5期21卷 954-965页

作者： Yongxian wei Xiu-Shen wei School of Computer Science and Technology Nanjing University of Science and TechnologyNanjing210094China

Localizing discriminative object parts(e.g.,bird head)is crucial for fine-grained classification tasks,especially for the more challenging fine-grained few-shot *** work always relies on the learned object parts in a unified manner,where they attend the same object parts(even with common attention weights)for different few-shot episodic *** this paper,we propose that it should adaptively capture the task-specific object parts that require attention for each few-shot task,since the parts that can distinguish different tasks are naturally *** for a few-shot task,after obtaining part-level deep features,we learn a task-specific part-based dictionary for both aligning and reweighting part features in an ***,part-level categorical prototypes are generated based on the part features of support data,which are later employed by calculating distances to classify query data for *** retain the discriminative ability of the part-level representations(i.e.,part features and part prototypes),we design an optimal transport solution that also utilizes query data in a transductive way to optimize the aforementioned distance calculation for the final *** experiments on five fine-grained benchmarks show the superiority of our method,especially for the 1-shot setting,gaining 0.12%,8.56%and 5.87%improvements over state-of-the-art methods on CUB,Stanford Dogs,and Stanford Cars,respectively.

关键词： Fine-grained image recognition few-shot learning transductive learning visual dictionary part feature discovery