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The feasibility analysis of the application of TPV system in reentry

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Science china(Technological Sciences) 2010年第12期53卷 3310-3315页

作者： YE Hong & GENG Xue department of Thermal Science and Energy engineering, university of Science and Technology of china, Hefei 230027, china 1. department of Thermal Science and Energy engineering University of Science and Technology of China Hefei 230027 China

A fundamental design of using thermophotovoltaic (TPV) system to convert the huge aerodynamic heat into electricity during the reentry process was described. The influences of heat conducting way, spectral filter and selective radiating surface on the system performance were analyzed in detail. The results showed that as a thermal conducting component, SiC is better than ablation material, with more electricity output but a larger cooling load, and that the adoption of spectral filter and selective radiating surface could lower the power output to some extent, yet diminish the cooling load prominently.

关键词： TPV reentry process spectral filter selective radiating surface

An atlas-based fuzzy connectedness method for automatic tissue classification in brain MRI

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Progress in Natural Science:Materials International 2006年第10期16卷 1106-1110页

作者： ZHOU Yongxin and BAI Jing (department of Biomedical engineering, Tsinghua university, Beijing 100084, china) [a]department of Biomedical engineering Tsinghua University Beijing China

A framework incorporating a subject-registered atlas into the fuzzy connectedness (FC) method is proposed for the automatic tissue classification of 3D images of brain MRI. The pre-labeled atlas is first registered onto the subject to provide an initial approximate segmentation. The initial segmentation is used to estimate the intensity histograms of gray matter and white matter. Based on the estimated intensity histograms, multiple seed voxels are assigned to each tissue automatically. The normalized intensity histograms are utilized in the FC method as the intensity probability density function (PDF) directly. Relative fuzzy connectedness technique is adopted in the final classification of gray matter and white matter. Experimental results based on the 20 data sets from IBSR are included, as well as comparisons of the performance of our method with that of other published methods. This method is fully automatic and operator-independent. Therefore, it is expected to find wide applications, such as 3D visualization, radiation therapy planning, and medical database construction.

关键词： fuzzy connectedness atlas-based segmentation brain tissue classification MR1.

Classification of Wavelet Bases by Translation Subgroups and Nonharmonic Wavelet Bases

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Acta Mathematica Sinica,English Series 2000年第2期16卷 307-312页

作者： Qiao Wang department of Radio engineering,Southeast university,Nanjing 210096,P.R.china department of Radio Engineerin Southeast University Nanjing 210096 P. R. China

The structure of the set S of shiftable points of wavelet subspaces is researched in this *** prove that S=R or S=(1/q)Z where q ∈ *** spectral and functional characterizations for the shiftability are ***,the nonhar... 详细信息

关键词： Wavelet Translation invariance Functional characterization

Stress Field Analyses of Functionally Gradient Ceramic Tool by FEM

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Journal of Materials Science & Technology 2001年第4期17卷 466-468页

作者： Ning FAN , Xing AI and Jun ZHAO department of Mechanical engineering, Shandong university,Jinan 250061, china Shandong Univ Dept Mech Engn Jinan 250061 Peoples R China

The cutting properties of the functionally gradient ceramic cutting tools relate closely to the gradient distribution. A cutting model of the functionally gradient ceramic tool is firstly designed in the present paper... 详细信息

关键词： Stress Field Analyses of Functionally Gradient Ceramic Tool by FEM Tool

A whisker-like carbon composite for the immobilization of laccase and its bioelectrochemistry

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Science china Chemistry 2010年第6期53卷 1332-1336页

作者： MA GuoXian1,2,ZHONG QingDong2 & LU TianHong3 1department of Chemical engineering,Shanghai Institute of Technology,Shanghai 200233,china 2School of Materials Science and engineering,Shanghai university,Shanghai 200072,china 3department of Chemistry,Nanjing Normal university,Nanjing 210097,china 1. department of Chemical engineering Shanghai Institute of Technology Shanghai 200233 China2. School of Materials Science and Engineering Shanghai University Shanghai 200072 China3. Department of Chemistry Nanjing Normal University Nanjing 210097 China

A novel mesoporous carbon/whisker-like carbon (MCWC) composite was used for the immobilization of laccase (Lac) and its bioelectrochemical behaviors were *** was confirmed by XPS that Lac was strongly adsorbed on the surface of the MCWC *** cyclic voltammetric results showed that the immobilized Lac underwent a direct quasi-reversible electrochemical *** value of the electron transfer rate constant ks was estimated to be 0.770 s-1,indicating a reasonably fast electron transfer between the immobilized Lac and the underlying *** surface concentration (I-) of Lac was estimated to be 2.730 × 10-12 mol/*** experimental results showed that the immobilized Lac displayed an appreciable electrocatalytic activity to the electrochemical reduction of *** properties could be attributed to the particular structure of loosely packed nanometer-scale carbon whiskers and the existence of a large amount of oxygen-containing *** immo- bilization method and the novel carrier (MCWC) may find new applications in fabricating the biocatalysts for biofuel cells.

关键词： laccase whisker-like carbon composite direct electrochemical reaction oxygen bioelectrochemistry

Semi-solid Processing of Al-7Graghite Composite

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Journal of university of Science and Technology Beijing 2001年第3期8卷 203-206页

作者： Peng Zhang, Yunhui Du, Daben Zeng department of Mechanical engineering, Tsinghua university, Beijing 100084, china Tsing Hua Univ Dept Engn Mech Beijing 100084 Peoples R China

Al-7graphite composite was processed using Al-7graphite mushy prepared by electromagnetic-mechanical stirring method, and the influence of solid fraction on the distributing of graphite particles in ingot was studied. The results shows that the relationship between solid fraction and stirring temperature of mushy is: f(s) = 591.5-0.897 t (where f(s) is the solid fraction, t is the stirring temperature). For Al-7graphite composite, with the increasing of solid fraction, the aggregation extent of graphite particles reduced gradually, and when solid fraction was larger than 30%, graphite particles could distribute evenly in ingot.

关键词： Al-7graphite composite electromagnetic-mechanical stirring method distributing of graphite particles solid fraction stirring temperature

LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE, MECHANISM AND MATERIAL DESIGNS

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Chinese Journal of Mechanical engineering 2004年第2期17卷 200-209页

作者： Mei Yulin Wang Xiaoming department of Mechanical engineering,Dalian university of Technology,Dalian 116024,china department of Mechanical engineering Dalian University of Technology Dalian 116024 China

Based on a level set model, a topology optimization method has been suggestedrecently. It uses a level set to express the moving structural boundary, which can flexibly handlecomplex topological changes. By combining vector level set models with gradient projectiontechnology, the level set method for topological optimization is extended to a topologicaloptimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, anappropriate nonlinear speed, mapping is established in the tangential space of the activeconstraints for a fast convergence. Then the method is applied to structure designs, mechanism andmaterial designs by a number of benchmark examples. Finally, in order to further improvecomputational efficiency and overcome the difficulty that the level set method cannot generate newmaterial interfaces during the optimization process, the topological derivative analysis isincorporated into the level set method for topological optimization, and a topological derivativeand level set algorithm for topological optimization is proposed.

关键词： Level set method Topology optimization Mean curvature flow Materialdesign Mechanism design Topological derivative

NUMERICAL DISSIPATION FOR THREE-POINT DIFFERENCE SCHEMES TO HYPERBOLIC EQUATIONS WITH UNEVEN MESHES

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Journal of Computational Mathematics 2003年第4期21卷 519-534页

作者： Zi-niu Wu(department of engineering Mechanics, Tsinghua university, Beijing 100084, china) department of engineering Mechanics Tsinghua University Beijing 100084 China

The widely used locally adaptive Cartesian grid methods involve a series of abruptly refined interfaces. The numerical dissipation due to these interfaces is studied here for three-point difference approximations of a hyperbolic equation. It will be shown that if the wave moves in the fine-to-coarse direction then the dissipation is positive (stabilizing), and if the wave moves in the coarse-to-fine direction then the dissipation is negative (destabilizing).

关键词： Refined interfaces Numerical dissipation Three-point difference approxima-tion Hyperbolic equation.

CALCULATION OF ADDED MASS OF A VEHICLE RUNNING WITH CAVITY

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Journal of Hydrodynamics 2010年第3期22卷 312-318页

作者： LI Jie LU Chuan-jing HUANG Xuan department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

A numerical method is developed to obtain the added mass coefficients of a vehicle running with cavity in numerical simulation for the multiphase flow of the vehicle which is imposed an added vibration and analyzing its hydrodynamic loads. The method is verified through the cases of non-cavitating sphere and ellipsoid. The changing rule of the added mass of a sphere during water exit is gained. Then the influence of cavitation on the added mass of a cylinder is studied. The results show that λ 11, λ22, λ26, λ66 all decrease as the cavitation number reduces and the length of the attached cavity increases. There is almost a linear relationship between the cavity length and λ22 .The base cavity has great influence on λ11 its contribution decreases more than 60%, when the cavitation number changes from 0.6 to 0.2.

关键词： added mass cavity carrying forced vibration method