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Hot Deformation Behavior and Microstructures Evolution of GNP-Reinforced Fine-Grained Mg Composites

Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 407-424页

作者： Hengrui Hu Jiayu Qin yunpeng zhu Jinhui Wang Xiaoqiang Li Peipeng Jin Qinghai Provincial Key Laboratory of New Light Alloys Qinghai UniversityXining 810016China Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming Qinghai UniversityXining 810016China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China School of Material Science and Engineering Lanzhou University of TechnologyLanzhou 730050China

Graphene nanoplates(GNPs)-reinforced magnesium matrix composites have been attracted great ***,knowledge is lack for the hot deformation behavior of GNP-reinforced magnesium(GNPs/Mg)*** this study,the fine-grained GNPs/Mg composite was fabricated by powder metallurgy process followed by *** hot deformation behavior,microstructure evolution and dynamic recrystallization(DRX)mechanism of fine-grained GNPs/Mg composite were investigated by hot compression test and electron back-scatter diffraction(EBSD).The hot compression tests of the composite were conducted at temperatures between 423 and 573 K with the strain rates from 0.001 to 1 s^(-1).The strain compensated power law equation was established to describe the hot deformation behavior of the *** stress exponent and activation energy of the composite are 7.76 and 83.23 kJ/mol,respectively,suggesting that the deformation mechanism is grain boundary slip controlled dislocation climb *** abnormally high stress exponent and activation energy are unattainable in the composite due to the fine grain size of the composites and the absence of Zener pinning and Orowan effects of GNPs *** grain size increases with the decrease in Zener-Hollomn(Z)parameter,which can be well fitted by power-law *** the increase in grain size and decrease in Z parameter,the geometrically necessary dislocation density decreases,which shows the approximately power-law relationship.A random and weak texture was formed after hot *** discontinuous dynamic recrystallization and continuous dynamic recrystallization mechanism dominated the DRX behavior at 473 K/0.001 s^(-1) and 573 K/0.001 s^(-1),respectively.

关键词： GNPs Mg composite Hot deformation behavior Constitutive equations Microstructure evolution Dynamic recrystallization

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Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

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原子能科学技术 2024年第4期58卷 705-713页

作者： HOU Lingxiao YUAN Youjin SHEN Guodong RUAN Shuang LIU Jie zhu yunpeng WANG Geng GUO Hongliang LYU Mingbang GAO Daqing XU Zhiguo SHENG Lina YANG Jiancheng Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle ***,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic ***,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal *** the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation *** order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam ***,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation *** mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at *** the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS *** this paper,the method and experimental results were introduced.

关键词： heavy ion accelerator beam uniformity scanning magnet MIC

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冠状动脉旁路移植术后卒中及其与颈-颅动脉病变相关性的研究进展

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中国胸心血管外科临床杂志 2024年第10期31卷 1538-1546页

作者：刘懿朱云鹏赵强上海交通大学医学院附属瑞金医院心血管外科上海200025

冠状动脉旁路移植术(coronary artery bypass grafting,CABG)是左主干及复杂多支冠状动脉病变血运重建治疗的“金标准”。CABG术后卒中是一种相对少见但具有灾难性后果的并发症,并造成严重的卫生经济负担。近年来,对“泛血管疾病”这一... 详细信息

冠状动脉旁路移植术(coronary artery bypass grafting,CABG)是左主干及复杂多支冠状动脉病变血运重建治疗的“金标准”。CABG术后卒中是一种相对少见但具有灾难性后果的并发症,并造成严重的卫生经济负担。近年来,对“泛血管疾病”这一概念的深入理解、“心脑一体化”诊疗理念的推行以及相关诊疗技术的提高,为该并发症的防治提供了新的选择。本文聚焦于颈-颅动脉病变这一关键因素,系统回顾了CABG术后卒中的发病率、流行病学现状、危险因素、发生机制及防治要点,分析了术后卒中与颈-颅动脉病变的关联,总结了预防性颈-颅动脉血运重建策略的循证依据,并对未来的研究方向做出展望。

关键词：冠状动脉旁路移植术脑卒中颈动脉病变颅内动脉病变颈动脉血运重建综述

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一种满足否定约束的增量数据修复算法

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计算机应用与软件 2024年第9期41卷 288-293,303页

作者：徐婷朱云鹏杨卫东谈子敬复旦大学计算机科学技术学院上海200438

为了提高数据质量,数据修复技术得到了广泛的研究。数据修复通常使用约束,常用的有函数依赖、条件函数依赖和否定约束(Denial Constraints, DCs)等,其中,否定约束具有足够的表达能力,可以包含许多其他依赖项,因此在数据修复中得到了很... 详细信息

为了提高数据质量,数据修复技术得到了广泛的研究。数据修复通常使用约束,常用的有函数依赖、条件函数依赖和否定约束(Denial Constraints, DCs)等,其中,否定约束具有足够的表达能力,可以包含许多其他依赖项,因此在数据修复中得到了很好的应用。另外,数据通常是动态的,因此需要增量修复技术,以响应数据更新。该文提出一种满足否定约束的增量修复算法,结合辅助的索引结构,能有效地识别增量数据引起的DC冲突。大量的实验结果表明了该方法的有效性和高效性。

关键词：数据质量否定约束增量修复

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大体积混凝土水化热损伤计算方法

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河海大学学报（自然科学版） 2024年第4期52卷 29-34页

作者：吕国儿汤群益王定仕李天昊诸云鹏陈达中国电建集团华东勘测设计研究院有限公司浙江杭州311122 河海大学港口海岸与近海工程学院江苏南京210098

为更准确地判断浇筑过程中大体积混凝土内部的水化热损失,提出了综合考虑混凝土绝热温升、环境温度、入模温度、模板材料散热系数、保温材料散热系数和浇筑层厚这6个影响因素的混凝土浇筑过程中最不利时刻的温度分布预测公式,并采用响... 详细信息

为更准确地判断浇筑过程中大体积混凝土内部的水化热损失,提出了综合考虑混凝土绝热温升、环境温度、入模温度、模板材料散热系数、保温材料散热系数和浇筑层厚这6个影响因素的混凝土浇筑过程中最不利时刻的温度分布预测公式,并采用响应面分析法率定公式中的参数,基于温度分布及Loland损伤模型提出了一种水化热损伤计算方法,通过有限元数值模型对该方法进行了验证。结果表明,该方法能够判断浇筑过程中任意一点是否会因为温度梯度造成损伤开裂。

关键词：温度损伤大体积混凝土水化热温度梯度响应面分析

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Comprehensive Reliability Allocation Method for CNC Lathes Based on Cubic Transformed Functions of Failure Mode and Effects Analysis

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Chinese Journal of Mechanical Engineering 2015年第2期28卷 315-324页

作者： YANG Zhou zhu yunpeng REN Hongrui ZHANG Yimin School of Mechanical Engineering & Automation Northeastern University

Reliability allocation of computerized numerical controlled（CNC）lathes is very important in *** allocation methods only focus on high-failure rate components rather than moderate failure rate components,which is not applicable in some *** at solving the problem of CNC lathes reliability allocating,a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis（FMEA）is ***,conventional reliability allocation methods are *** the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are ***,a cubic transformed function is established in order to overcome these *** of the new transformed functions are discussed by considering the failure severity and the failure *** can choose appropriate transform amplitudes according to their ***,a CNC lathe and a spindle system are used as an example to verify the new allocation *** criteria are considered to compare the results of the new method with traditional *** allocation results indicate that the new method is more flexible than traditional *** employing the new cubic transformed function,the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods.

关键词： CNC lathes reliability failure modes and effects analysis(FMEA) cubic transformed function comprehensive allocation

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Dynamics Analysis of Active Variable Stiffness Vibration Isolator for Whole-Spacecraft Systems Based on Nonlinear Output Frequency Response Functions

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Acta Mechanica Solida Sinica 2020年第6期33卷 731-743页

作者： Kefan Xu Yewei Zhang yunpeng zhu Jian Zang Liqun Chen College of Aerospace Engineering Shenyang Aerospace UniversityShenyang 110136China Department of Automatic Control and Systems Engineering Sheffield UniversityMapping StreetSheffield SI 3JDUK Harbin Institute of Technology Shenzhen 518055China

In order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations,this study presents a novel active variable stiffness vibration isolator(AVS-VI)used as the vibration isolation device to reduce excessive vibration of the whole-spacecraft isolation *** AVS-VI is composed of horizontal stiffness spring,positive stiffness spring,parallelogram linkage mechanism,piezoelectric actuator,acceleration sensor,viscoelastic damping,and PID active *** on the AVS-VI,the generalized vibration transmissibility determined by the nonlinear output frequency response functions and the energy absorption rate is applied to analyze the isolation performance of the whole-spacecraft system with *** AVS-VI can conduct adaptive vibration suppression with variable stiffness to the whole-spacecraft system,and the analysis results indicate that the AVS-VI is efTective in reducing the extravagant vibration of the whole-spacecraft system,where the vibration isolation is decreased up to above 65%under different acceleration ***,different parameters of AVS-VI are considered to optimize the whole-spacecraft system based on the generalized vibration transmissibility and the energy absorption rate.

关键词： Vibration isolation Active variable stiffness vibration isolator Nonlinear output frequency response functions(NOFRFs) Transmissibility

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PRESS-based EFOR algorithm for the dynamic parametrical modeling of nonlinear MDOF systems

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Frontiers of Mechanical Engineering 2018年第3期13卷 390-400页

作者： Haopeng LIU yunpeng zhu Zhong LUO Qingkai HAN School of Mechanical Engineering and Automation Northeaste University Shenyang 110819 China Key Laboratory of Vibration and Control of Aero-Propulsion Systems (Ministry of Education) Northeastern University Shenyang 110819 China Departrnent of Automatic Control and System Engineering Sheffield University Sheffield S13JD UK School of Mechanical Engineering Dalian University of Technology Dalian 116023 China

In response to the identification problem concerning multi-degree of freedom （MDOF） nonlinear systems, this study presents the extended forward orthogonal regression （EFOR） based on predicted residual sums of squares （PRESS） to construct a nonlinear dynamic parametrical model. The proposed parametrical model is based on the non-linear autoregressive with exogenous inputs （NARX） model and aims to explicitly reveal the physical design parameters of the system. The PRESSbased EFOR algorithm is proposed to identify such a model for MDOF systems. By using the algorithm, we built a common-structured model based on the fundamental concept of evaluating its generalization capability through cross-validation. The resulting model aims to prevent over-fitting with poor generalization performance caused by the average error reduction ratio （AERR）-based EFOR algorithm. Then, a functional relationship is established between the coefficients of the terms and the design parameters of the unified model. Moreover, a 5- DOF nonlinear system is taken as a case to illustrate the modeling of the proposed algorithm. Finally, a dynamic parametrical model of a cantilever beam is constructed from experimental data. Results indicate that the dynamic parametrical model of nonlinear systems, which depends on the PRESS-based EFOR, can accurately predict the output response, thus providing a theoretical basis for the optimal design of modeling methods for MDOF nonlinear systems.

关键词： MDOF dynamic parametrical model NARX model PRESS-based EFOR cantilever beam

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Similitude design for the vibration problems of plates and shells： A review

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Frontiers of Mechanical Engineering 2017年第2期12卷 253-264页

作者： yunpeng zhu You WANG Zhong LUO Qingkai HAN Deyou WANG Department of Automatic Control and System Engineering SheffieldUniversity Sheffield S13JD UK School of Mechanical Engineering and Automation NortheasternUniversity Shenyang 110819 China School of Mechanical Engineering Dalian University of TechnologyDalian 116023 China AECC Shenyang Aero-engine Institute Shenyang 110042 China

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achieve- ments of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

关键词： review dynamic similitude vibration modeltest

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Dynamic design of a nonlinear energy sink with NiTiNOL-steel wire ropes based on nonlinear output frequency response functions

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Applied Mathematics and Mechanics(English Edition) 2019年第12期40卷 1791-1804页

作者： Yewei ZHANG Kefan XU Jian ZANG Zhiyu NI yunpeng zhu Liqun CHEN College of Aerospace Engineering Shenyang Aerospace UniversityShenyang 110136China Department of Automatic Control and Systems Engineering Sheffield UniversityMapping Street Sheffield S13JDU.K. Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China School of Mechanics and Engineering Science Shanghai UniversityShanghai 200444China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai 200072China

A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft *** NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of *** NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with *** generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the *** optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of ***,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy *** results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural ***,the NES with NiTi-ST can be directly used in practical engineering applications.

关键词： nonlinear energy sink(NES) vibration isolation NiTiNOL-steel wire rope (NiTi-ST) nonlinear output frequency response function(NOFRF) root mean square transmissibility

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