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Theoretical models for irradiation hardening and embrittlement in nuclear structural materials:a review and perspective

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Acta Mechanica Sinica 2020年第2期36卷 397-411页

作者： Xiazi xiao Dmitry Terentyev Haijian Chu Huiling duan Department of Mechanics School of Civil EngineeringCentral South UniversityChangsha 410075China Structural Materials Group Institute of Nuclear Materials ScienceSCK-CEN2400 MolBelgium Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China CAPT HEDPS and IFSA CollaborativeInnovation Center of MoEBIC-ESATPeking UniversityBeijing 100871China

The study of irradiation hardening and embrittlement is critically important for the development of next-generation structural materials tolerant to neutron irradiation,and could dramatically affect the approach to the design of components for advanced nuclear *** addition,a growing interest is observed in the field of research and development of irradiation-resistant *** review aims to provide an overview of the theoretical development related to irradiation hardening and embrittlement at moderate irradiation conditions achieved in recent years,which can help extend our fundamental knowledge on nuclear structural *** a general introduction to the irradiation effects on metallic materials,recent research progress covering theoretical modelling is summarized for different types of structural *** fundamental mechanisms are elucidated within a wide range of temporal and spatial *** review closes with the current understanding of irradiation hardening and embrittlement,and puts some perspectives deserving further study.

关键词： Irradiation hardening Irradiation embrittlement Theoretical models Fundamental mechanisms

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Joint Sample Position Based Noise Filtering and Mean Shift Clustering for Imbalanced Classification Learning

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Tsinghua Science and Technology 2024年第1期29卷 216-231页

作者： Lilong duan Wei Xue Jun Huang xiao Zheng School of Computer Science and Technology Anhui University of TechnologyMaanshan 243032China Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China

The problem of imbalanced data classification learning has received much *** classification algorithms are susceptible to data skew to favor majority samples and ignore minority *** weighted minority oversampling technique(MWMOTE)is an effective approach to solve this problem,however,it may suffer from the shortcomings of inadequate noise filtering and synthesizing the same samples as the original minority *** this end,we propose an improved MWMOTE method named joint sample position based noise filtering and mean shift clustering(SPMSC)to solve these ***,in order to effectively eliminate the effect of noisy samples,SPMsC uses a new noise filtering mechanism to determine whether a minority sample is noisy or not based on its position and distribution relative to the majority *** that MWMOTE may generate duplicate samples,we then employ the mean shift algorithm to cluster minority samples to reduce synthetic replicate ***,data cleaning is performed on the processed data to further eliminate class *** on extensive benchmark datasets demonstrate the effectiveness of SPMsC compared with other sampling methods.

关键词： imbalanced data classification oversampling noise filtering clustering

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Flight mechanism and design of biomimetic micro air vehicles

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Science China(Technological Sciences) 2009年第12期52卷 3722-3728页

作者： ANG HaiSong xiao TianHang duan WenBo Research Center of Micro Air Vehicle Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper summaries the investigations on natural flyers and development of bio-mimetic micro air vehicles(MAVs)at NUAA,China,where the authors have led a group to conduct research for a decade. The investigations include the studies of low Reynolds number aerodynamics,unsteady computational fluid dynamics and flight control for the fixed-wing MAVs,the bird-like MAVs,the dragonfly-like MAVs and the bee-like MAVs.

关键词： biomimetics micro air vehicles aerodynamics configuration design

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Multi-robot hunting strategy based on FIS and artificial immune algorithm

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High Technology Letters 2019年第1期25卷 57-64页

作者： duan Yong Huang xiao Shenyang University of Technology

data is gathered to describe the relative location and relative motion state of the robots, which in turn forms the beginning stage of the fuzzy rule. The artificial immune algorithm optimizes and generates the rule data base and adaptive design considers factors in measuring the hunting efficiency. The optimized rules are applied to the hunting task and the results show that the algorithm can effectively actualize hunting of multiple mobile robots.

关键词： multi-robot hunting fuzzy inference system(FIS) artificial immunity fuzzy rule database

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Degree elevation of unified and extended spline curves

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第12期15卷 1098-1105页

作者： xiao-juan duan Guo-zhao WANG Department of Mathematics Zhejiang University

Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this paper is the degree elevation algorithm of UE-spline curves and its geometric meaning. Our main idea is to elevate the degree of UE-spline curves one knot interval by one knot interval. First, we construct a new class of basis functions, called bi-order UE-spline basis functions which are defined by the integral definition of *** some important properties of bi-order UE-splines are given, especially for the transformation formulae of the basis functions before and after inserting a knot into the knot vector. Finally, we prove that the degree elevation of UE-spline curves can be interpreted as a process of corner cutting on the control polygons, just as in the manner of B-splines. This degree elevation algorithm possesses strong geometric intuition.

关键词： Degree elevation Unified and extended splines(UE-splines) Bi-order UE-splines Corner cutting Geometric explanation

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A Direct Parametric Approach to Spacecraft Attitude Tracking Control

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International Journal of Automation and computing 2017年第5期14卷 626-636页

作者： xiao-Yi Wang Guang-Ren duan Center for Control Theory and Cuidance Technology Harbin Institute of TechnologyHarbin 150001China

Through the direct parameter approach, a solution for spacecraft attitude tracking is presented. First of all, the spacecraft attitude tracking control model is built up by the error equation of the second-order nonlinear quaternion-based attitude system. Based on the control model, a suitable controller is designed by the direct parameter approach. Compared with other control strategies, the direct parameter approach can offer all degrees of freedom for the controller to satisfy the requirements for system properties and turn the original nonlinear system into closed-loop linear system. Furthermore, this paper optimizes the controller according to the robustness, limitation of controller output and closed-loop eigenvalue sensitivity. Putting the controller into the original system, the state response of the closed-loop system and the output of controller are plotted in Matlab to verify the availability and robustness of the controller. Therefore, the controlled spacecraft can achieve the goal of tracking on the mobile target with the external disturbance torque.

关键词： Nonlinear systems attitude control spacecraft attitude tracking quaternion representation direct parametric approach.

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NUAT T-splines of odd bi-degree and local refinement

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Applied Mathematics(A Journal of Chinese Universities) 2014年第4期29卷 410-421页

作者： duan xiao-juan WANG Guo-zhao Department of Mathematics Zhejiang University

This paper presents a new kind of spline surfaces, named non-uniform algebraic- trigonometric T-spline surfaces （NUAT T-splines for short） of odd hi-degree. The NUAT T- spline surfaces are defined by applying the T-spline framework to the non-uniform algebraic- trigonometric B-spline surfaces （NUAT B-spline surfaces）. Based on the knot insertion algorithm of the NUAT B-splines, a local refinement algorithm for the NUAT T-splines is given. This algorithm guarantees that the resulting control grid is a T-mesh as the original one. Finally, we prove that, for any NUAT T-spline of odd hi-degree, the linear independence of its blending functions can be determined by computing the rank of the NUAT T-spline-to-NUAT B-spline transformation matrix.

关键词： odd bi-degree non-uniform algebraic-trigonometric T-spline local refinement blending function,linear independence.

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Microstructure-mechanical property relationship in Ti-Mo microalloyed steel with random and interphase precipitates

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Journal of Iron and Steel Research International 2019年第8期26卷 838-845页

作者： Hai-long Yi Lu-ran Zhang Rui-hai duan Xin-zeng Liang State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China

The relationship between microstructure and mechanical properties of Ti-Mo microalloyed steels composed of ferrite and bainite with nanometer-sized carbides and isothermally transformed at different temperatures and time was systematically investigated by tensile test, hardness test, and transmission electron microscopy. Ferrite formed at high temperatures exhibited both planar/curved sheet-like dispersions of interphase precipitates and random dispersion precipitates, with the interphase precipitates being the dominant morphology. In contrast, bainite formed at low temperatures exhibited only random dispersion precipitates. Furthermore, random dispersion precipitates and interphase precipitates were observed within the same ferrite grains. The mechanical properties of the ferrite specimen were superior to those of the bainite specimen. The stress-strain curves of both specimens indicated continuous yielding, high strength, and sufficient tensile elongation. The strengthening of the ferrite specimen was attributed to grain size strengthening, dislocation strengthening, and precipitation hardening, and the degree of precipitation strengthening was approximately 300 MPa.

关键词： Mechanical property Interphase precipitate Dispersion precipitate Precipitation strengthening Ti-Mo microalloyed stee

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Progress on metal-support interactions in Pd-based catalysts for automobile emission control

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Journal of Environmental Sciences 2023年第3期125卷 401-426页

作者： Yidan Cao Rui ran xiaodong Wu Zhichun Si Feiyu Kang duan Weng Institute of Materials Research Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Tsinghua-Berkeley Shenzhen Institute Tsinghua UniversityShenzhen 518055China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

The interactions between metals and oxide supports,so-called metal-support interactions(MSI),are of great importance in heterogeneous ***-based automotive exhaust control catalysts,especially Pd-based three-way catalysts (TWCs),have received considerable research attention owing to its prominent oxidation activity of HCs/CO,as well as excellent thermal *** Pd-based TWCs,the dispersion,chemical state and thermal stability of Pd species,which are crucial to the catalytic performance,are closely associated with interactions between metal nanoparticles and their supporting *** on the research about MSI and utilization of MSI in advanced Pd-based three-way catalysts are reviewed *** with the development of advanced synthesis approaches and engine control technology,the study on MSI would play a notable role in further development of catalysts for automobile exhaust control.

关键词： Palladium Three-way catalysts(TWCs) Metal-support interaction Oxide supports

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Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

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Journal of Environmental Sciences 2019年第7期31卷 43-51页

作者： Yue Ma xiaodong Wu Junyu Zhang Rui ran Zhichun Si duan Weng The Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and Engineering Tsinghua University School of Environment Tsinghua University Graduate School at Shenzhen Tsinghua University

Selective catalytic reduction(SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of CuSAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.

关键词： SCR Urea Biuret Cu-SAPO-34 Deactivation

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