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Anomalous residual austenite formation in root of welding layers of 9% Cr/CrMoV dissimilar welded joint

Journal of Iron and Steel Research International 2018年第8期25卷 839-846页

作者： Kai Ding hui-jun Ji quan-liang Zhang Xia Liu peng Wang Xiao-hong Li Ling Zhang Yu-lai Gao State Key Laboratory of Advanced Special Steel State Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and Engineering Shanghai University Shanghai 200444 China Shanghai Turbine Plant Shanghai Electric Power Generation Equipment Co. Ltd. Shanghai 200240 China

The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.

关键词： Residual austenite Color metallographic method Dissimilar welded joint Narrow gap submerged arcwelding Multilayer and multi-pass welding

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Diameter Modification of Si Nanowires via Catalyst Size

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Chinese Physics Letters 2003年第5期20卷 700-702页

作者： XINGYing-Jie XIZhong-He XUEZeng-quan YUDa-peng DepartmentofElectronics PekingUniveristyBeijing100871 SchoolofPhysics MesoscopicPhysicsNationalLaboratoryandElectronMiroscopyLaboratoryPekingUniversityBeijing100871

Si nanowires with different diameters are grown on catalyst coated Si substrates via a solid-liquid-solid mechanism. It is found that the thickness and type of catalyst film can modify the average diameter of Si nanowires obviously. The nanowires prepared on substrates deposited with Ni film of 40, 10, and 4nm thick have a mean diameter around 41, 36, and 24nm, respectively. Si nanowires with the smallest average diameter (~16nm) are grown with a gold catalyst. Studies of diameter distributions show that the minimum diameter of nanowires does not shift with the average diameters spontaneously and has the same size of 10nm.

关键词：硅基底直径薄膜厚度尺寸催化剂薄膜生长

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Optimal dynamical systems of Navier-Stokes equations based on generalized helical-wave bases and the fundamental elements of turbulence

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Science China(Physics,Mechanics & Astronomy) 2016年第11期59卷 61-69页

作者： NaiFu peng hui Guan ChuiJie Wu State Key Laboratory of Structural Analysis for Industrial Equipment School of Aeronautics and AstronauticsDalian University of Technology State Key Laboratory for Turbulence and Complex Systems Center for Applied Physics and TechnologyCollege of Engineering Peking University College of Meteorology and Oceanography PLA University of Science and Technology

In this paper, we present the theory of constructing optimal generalized helical-wave coupling dynamical systems. Applying the helical-wave decomposition method to Navier-Stokes equations, we derive a pair of coupling dynamical systems based on optimal generalized helical-wave bases. Then with the method of multi-scale global optimization based on coarse graining analysis, a set of global optimal generalized helical-wave bases is obtained. Optimal generalized helical-wave bases retain the good properties of classical helical-wave bases. Moreover, they are optimal for the dynamical systems of Navier-Stokes equations, and suitable for complex physical and geometric boundary conditions. Then we find that the optimal generalized helical-wave vortexes fitted by a finite number of optimal generalized helical-wave bases can be used as the fundamental elements of turbulence, and have important significance for studying physical properties of complex flows and turbulent vortex structures in a deeper level.

关键词： optimal dynamical systems helical-wave decomposition fundamental elements of turbulence vortex structures

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Research on the optimal dynamical systems of three-dimensional Navier-Stokes equations based on weighted residual

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Science China(Physics,Mechanics & Astronomy) 2016年第4期59卷 78-85页

In this paper, the theory of constructing optimal dynamical systems based on weighted residual presented by Wu & Sha is applied to three-dimensional Navier-Stokes equations, and the optimal dynamical system modeling equations are derived. Then the multiscale global optimization method based on coarse graining analysis is presented, by which a set of approximate global optimal bases is directly obtained from Navier-Stokes equations and the construction of optimal dynamical systems is realized. The optimal bases show good properties, such as showing the physical properties of complex flows and the turbulent vortex structures, being intrinsic to real physical problem and dynamical systems, and having scaling symmetry in mathematics, etc.. In conclusion, using fewer terms of optimal bases will approach the exact solutions of Navier-Stokes equations, and the dynamical systems based on them show the most optimal behavior.

关键词： optimal dynamical systems weighted residual three-dimensional Navier-Stokes equations vortex structures

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Territorial suitability assessment and function zoning in the Jiuzhaigou earthquake-stricken area

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Journal of Mountain Science 2019年第1期16卷 195-206页

作者： YU hui QIANG Miao LIU Shao-quan Institute of Mountain Hazards and Environment Chinese Academy of Sciences University of Chinese Academy of Sciences Chengdu Pidu Disstrict Mianshi Foreign Language School

An earthquake in the Jiuzhaigou area caused numerous secondary disasters, such as rolling stones, land collapse, landslides and debris flow, which badly affected the safety of human settlements and influenced the spatial layout of the post-disaster reconstruction. Therefore, carrying out assessments of land and identifying a suitable zone for human habitats were very important. This research creates the territorial suitability assessment and function zoning conceptual model in the earthquake-stricken area, and the new methods of the territorial suitability evaluation system were used to divide the spatial functional zones of the earthquake stricken area, which provide a theoretical guidance and decisionmaking basis for the reconstruction of the disaster area. The results showed that:(1) The Jiuzhaigou earthquake-stricken area comprises of an ecological area that has a high level of importance to the ecosystem. In the earthquake-stricken area, 65% of national land is at an altitude of 3000-4000 m, and therefore not suitable for a high level of intensive reconstruction, but reconstructed in an eco-friendly manner.(2) The zone suitable for reconstruction comprises mainly of the river valley and the flat terrain of western parts. The land with low suitability is mainly located on steep terrain, such as highmountains and low gullies. The geographic and geomorphic conditions limit the spread of a suitable reconstruction zone.(3) The earthquake-stricken area mainly comprises of a tourism industry gathering area, population gathering area, agriculture and animal husbandry development area, and ecological preservation area with areas of 76 km^2, 44 km^2, 1591 km^2 and 7512 km^2, respectively. Scientifically zoning the reconstruction areas using scientific evaluation may provide guidance for the location of reconstruction sites.

关键词： Jiuzhaigou valley Earthquake-stricken area Territorial suitability Function zoning

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;unctional metabolomics： from biomarker ：liscovery to metabolome reprogramming

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Protein & Cell 2015年第9期6卷 628-637页

作者： Bo peng hui Li Xuan-Xian peng Center for Proteomics and Metabolomics State Key Laboratory of Biocontrol School of Life Sciences MOE Key Lab Aquat Food Safety School of Life Sciences Sun Yat-sen University Guangzhou 510275 China Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA 94720 USA

Metabolomics is emerging as a powerful tool for studying metabolic processes, identifying crucial biomarkers responsible for metabolic characteristics and revealing metabolic mechanisms, which construct the content of discovery metabolomics. The crucial biomarkers can be used to reprogram a metabolome, leading to an aimed metabolic strategy to cope with alteration of internal and external environments, naming reprogramming metabo- Iomics here. The striking feature on the similarity of the basic metabolic pathways and components among vastly different species makes the reprogramming metabolomics possible when the engineered metabolites play biological roles in cellular activity as a substrate of enzymes and a regulator to other molecules including proteins. The reprogramming metabolomics approach can be used to clarify metabolic mechanisms of responding to changed internal and external environmental factors and to estab- lish a framework to develop targeted tools for dealing with the changes such as controlling and/or preventing infec- tion with pathogens and enhancing host immunity against pathogens. This review introduces the current state and trends of discovery metabolomics and reprogramming metabolomics and highlights the importance of repro- gramming metabolomics.

关键词： reprogrammingregulationmetabolomics discovery metabolomicsmetabolomics metabolic strategy metabolic

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Metal-Backboned Polymer:Conception,Design and Synthesis

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Chinese Journal of Polymer Science 2023年第1期41卷 3-6页

作者： Kai-Wen Zeng hui-Sheng peng State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science Fudan UniversityShanghai200438China

The backbones of polymers are generally composed of non-metal elements such as C,N,O and *** we propose and synthesize a new class of polymers whose backbones are completely made from metal atoms connected by chemical bonds,and they are thus named metal-backboned *** a demonstration,nickel is selected as the metal to construct the nickel-backboned polymers with varied lengths,which are verified by mass spectrometry and studied by ultraviolet-visible *** metal-bonded polymers open up a new avenue to develop functional polymers in the future.

关键词： Metal-backboned Nickel Functional Polymer

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Effects of shear-thinning/thickening nature on the stability of Couette-like flow with uniform crossflow

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Acta Mechanica Sinica 2013年第6期29卷 806-810页

作者： Yu-quan Liu Jie peng Ke-Qin Zhu Department of Engineering Mechanics Tsinghua University

The linear stability of wall-injected pressure- driven Couette-like flow in power-law fluids is studied. Previous study on this kind of flow for Newtonian fluids by Nicoud and Angilella [Phys. Rev. E 56, 3000 （1997）] was extended to power-law fluids to understand the effects of shear-thinning/thickening nature on the flow stability. A related expression between the critical crossflow Reynolds number for Newtonian fluids and that for power-law fluids is obtained as the streamwise Reynolds number is large enough based on numerical computations, and verified theoretically in the case of a limiting condition with the power-law index.

关键词： Power-law fluid Couette-like flow - Crossflow Linear stability

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Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

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Chinese Journal of Aeronautics 2014年第6期27卷 1343-1351页

作者： Tian hui Li Yijie Zeng peng School of Astronautics Beihang University

The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion *** mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB（hydroxyl-terminated polybutadiene） hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

关键词： Dynamic mesh Flow throttling process Hybrid rocket motor Numerical simulation Transient regression rate

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Parameter estimation in exponential models by linear and nonlinear fitting methods

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Frontiers of Information Technology & Electronic Engineering 2017年第3期18卷 434-444页

作者： Ping YANG Chao-peng WU Yi-lu GUO Hong-bo LIU hui HUANG Hang-zhou WANG Shu-yue ZHAN Bang-yi TAO quan-quan MU Qiang WANG Hong SONG School of Digital Media & Design Hangzhou Dianzi University Ocean College Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration State Key Laboratory of Applied Optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of Sciences

Estimation of unknown parameters in exponential models by linear and nonlinear fitting methods is discussed. Based on the extreme value theorem and Taylor series expansion, it is proved theoretically that the parameters estimated by the linear fitting method alone cannot minimize the sum of the squared residual errors in the measurement data when measurement noise is involved in the data. Numerical simulation is performed to compare the performance of the linear and nonlinear fitting methods. Simulation results show that the linear method can obtain only a suboptimal estimate of the unknown parameters and that the nonlinear method gives more accurate results. Application of the fitting methods is demonstrated where the water spectral attenuation coefficient is estimated from underwater images and imaging distances, which supports the improvement in the accuracy of parameter estimation by the nonlinear fitting method.

关键词： Exponential model Parameter estimation Linear least squares Nonlinear fitting

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