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纳米晶NiTi记忆合金应力诱发R→B19′相变的超弹稳定性

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材料热处理学报 2024年第5期45卷 94-99页

作者：王涛涛武泽园李亚鹏廖仲尼王永善陕西理工大学材料科学与工程学院陕西汉中723001

通过对Ni_(50.2)Ti_(49.8)(at%)记忆合金丝材进行大变形冷拔和低温退火获得了平均晶粒尺寸为15 nm的纳米晶NiTi记忆合金丝材样品,然后采用应变量为6%的20次拉伸循环实验研究了纳米晶NiTi合金力致R→B19′相变的超弹稳定性。结果表明:纳... 详细信息

通过对Ni_(50.2)Ti_(49.8)(at%)记忆合金丝材进行大变形冷拔和低温退火获得了平均晶粒尺寸为15 nm的纳米晶NiTi记忆合金丝材样品,然后采用应变量为6%的20次拉伸循环实验研究了纳米晶NiTi合金力致R→B19′相变的超弹稳定性。结果表明:纳米晶NiTi合金在经过20次拉伸循环变形后,其超弹应力为734 MPa,超弹应力的减小率为16%,残余应变为0.61%,此综合超弹性能优于以往粗晶NiTi记忆合金。这主要源于纳米晶NiTi记忆合金中细晶强化显著提高了合金屈服强度,因此降低合金马氏体相变过程中塑性变形,可使纳米晶NiTi记忆合金呈现高的超弹稳定性。

关键词：纳米晶 NiTi 记忆合金 R相超弹稳定性

Wind-induced response analysis of a wind turbine tower including the blade-tower coupling effect

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第11期10卷 1573-1580页

作者： Xiao-bo CHEN Jing li jian-yun CHEN School of Civil and Hydraulie Engineering Dalian University of Technology Dalian 116024 China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.

关键词： Fluctuating wind velocity Mean wind velocity Tower Blade Coupling Wind shear effect Vibration

Environmental effects induced by excavation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 50-57页

作者： Yu-qi li jian ZHOU Kang-he XIE Department of Civil Engineering Shanghai University Shanghai 200072 China Department of Geotechnical Engineering Tongji University Shanghai 200092 China Institute of Geotechnical Engineering Zhejiang University Hangzhou 310027 China

Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit de- formations of the former are larger than those of the latter, so that the result without considering the variation of water head dif- ference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.

关键词： Environmental effect Excavation Deformation Excess porewater pressure

神经外科术后泛耐药鲍曼不动杆菌颅内感染患儿一例

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中华重症医学电子杂志 2024年第2期10卷 205-208页

作者：邓小鹿赵杰李健李春辉何剑司道林王霞中南大学湘雅医院儿科长沙410008 中南大学湘雅医院神经外科长沙410008 中南大学湘雅医院感染控制中心长沙410008

医疗相关脑室炎和脑膜炎(HCAVM)与神经外科手术密切相关。HCAVM最常由革兰氏阳性菌引起,但近年革兰氏阴性菌感染呈现上升趋势。广泛耐药(XDR)革兰氏阴性菌所致的颅内感染可导致严重的后遗症,病死率高。本文报道1例神经外科术后XDR鲍曼... 详细信息

医疗相关脑室炎和脑膜炎(HCAVM)与神经外科手术密切相关。HCAVM最常由革兰氏阳性菌引起,但近年革兰氏阴性菌感染呈现上升趋势。广泛耐药(XDR)革兰氏阴性菌所致的颅内感染可导致严重的后遗症,病死率高。本文报道1例神经外科术后XDR鲍曼不动杆菌脑室炎患者,通过多学科合作治愈,以期为类似疾病的成功诊治提供经验。

关键词：颅内感染泛耐药鲍曼不动杆菌多黏菌素

Effect of yttrium modification on the corrosion behavior of AZ63 magnesium alloy in sodium chloride solution

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Journal of Magnesium and Alloys 2021年第2期9卷 613-626页

作者： Jiarun li Zhuoyuan Chen jiangping Jing jian Hou Key Laboratory of Marine Environmental Corrosion and Bio-fouling Institute of OceanologyChinese Academy of Sciences7 Nanhai RoadQingdao 266071China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research InstituteWenhai RoadQingdao 266237China Center for Ocean Mega-Science Chinese Academy of Sciences7 Nanhai RoadQingdao 266071China Open Studio for Marine Corrosion and Protection Pilot National Laboratory for Marine Science and Technology(Qingdao)No.1 Wenhai RoadQingdao 266237China

The microstructures and corrosion behaviors of Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(0.251.0)%Y in 3.5 wt.%Na Cl solution are investigated via morphology observation,phase characterization,immersion and electrochemical *** experimental results suggest that yttrium alloying can improve the corrosion resistance of Mg-6%Al-3%Zn throughout the *** initial enhanced corrosion resistance of magnesium alloy is attributed to the Y alloying,which gives rise to the increasing content of Al_(2)O_(3)in oxide *** promoted protectiveness of oxide layer on Mg-6%Al-3%Zn-1.0%Y alloy arouse a filiform corrosion as revealed by in-situ metallographic ***,the Y-containing magnesium alloys still perform higher corrosion resistance compared with that of Mg-6%Al-3%Zn alloy even if the oxide layer is *** phenomenon is owing to two factors,one is the gradual transformation of intermetallic phases from continuous Mg_(17)Al_(12)to discrete Al_(2)Y in matrix,by which the micro-galvanic corrosion betweenα-Mg grains and intermetallic phases is alleviated;the other is the morphology variation of corrosion products,the uniform and compact products layer on Y-containing alloys provide a barrier that effectively prevent the corrosive ions from penetrating into and reacting with Mg matrix.

关键词： Magnesium Yttrium alloying Corrosion Intermetallic phase Oxide layer

Nonlinear vibration analysis of a circular composite plate harvester via harmonic balance

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Acta Mechanica Sinica 2019年第4期35卷 912-925页

作者： Tian-Chen Yuan jian Yang li-Qun Chen shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China School of Urban Railway Transportation Shanghai University of Engineering Science Shanghai 201620 China Department of Mechanics Shanghai University Shanghai 200444 China shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University Shanghai 200072 China

Alumped parameter transversevibration model of a composite plate harvester is analyzed via harmonic balance approaches. The harvester is mainly composed of a piezoelectriccircular composite clamped by two steel rings and a proof mass on the *** lumped parameter model is a 1.5 degree-of-freedom strongly nonlinear system with a higher order polynomial stiffness. Aharmonic balance approach is developed to analyze the system, and the resulting algebraic equations are numerically solved by adopting an arc-length continuation technique. Anincremental harmonic balance approach is also developedfor the lumped parameter model. The two approaches yieldthe same *** amplitude-frequency responses produced by the harmonic balance approach are validated by the numericalintegrations and the experimental data. The investigation reveals that there coexist hardening and softening characteristics in the amplitude-frequency response curves under sufficiently large excitations. The harvester with thecoexistenceof hardening and softening nonlinearitiescan outperform not only linear energy harvesters but also typical hardening nonlinear energy harvesters.

关键词： Piezoelectricenergy harvester Circular composite plate Transverse nonlinear vibration Harmonic balance Arc-length continuation

Event-triggered adaptive control for attitude tracking of spacecraft

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Chinese Journal of Aeronautics 2019年第2期32卷 454-462页

作者： Chenliang WANG Yun li Qinglei HU jian HUANG School of Automation Science and Electrical Engineering Beihang University Beijing Institute of Automatic Control Equipment

Plug-and-play technology is an important direction for future development of spacecraft and how to design controllers with less communication burden and satisfactory performance is of great importance for plug-and-play spacecraft. Considering attitude tracking of such spacecraft with unknown inertial parameters and unknown disturbances, an event-triggered adaptive backstepping controller is designed in this paper. Particularly, a switching threshold strategy is employed to design the event-triggering mechanism. By introducing a new linear time-varying model, a smooth function, an integrable auxiliary signal and a bound estimation approach, the impacts of the network-induced error and the disturbances are effectively compensated for and Zeno phenomenon is successfully avoided. It is shown that all signals of the closed-loop system are globally uniformly bounded and both the attitude tracking error and the angular velocity tracking error converge to zero. Compared with conventional control schemes, the proposed scheme significantly reduces the communication burden while providing stable and accurate response for attitude maneuvers. Simulation results are presented to illustrate the effectiveness of the proposed scheme.

关键词： Adaptive control Attitude tracking Event-triggered control Spacecraft Uncertainties

Responses of benthic foraminifera to changes of temperature and salinity:Results from a laboratory culture experiment

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Science China Earth Sciences 2019年第2期62卷 459-472页

作者： Shuaishuai DONG Yanli LEI Tiegang li Zhimin jian Department of Marine Organism Taxonomy & Phylogeny Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences Center for Ocean Mega-Science Chinese Academy of Sciences Key Laboratory of Marine Sedimentology and Environmental Geology First Institute of Oceanography SOA Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Marine Geology Tongji University

The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18℃) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12℃, 25 psu and the lowest at 6℃, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially,temperature by shifting foraminiferal species composition and altering the community parameters.

关键词： Benthic foraminifera Community parameter Temperature Salinity Culture experiment Intertidal zone

Roundtable： Research Opportunities and Challenges for Large-Scale Software Systems

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Journal of Computer Science & Technology 2016年第5期31卷 851-860页

作者： Xusheng Xiao jian-Guang Lou shan Lu David C. Shepherd Xin Peng Qian-Xiang Wang NEC Laboratories America Princeton NJ 08540 U.S.A. Microsoft Research Asia Beijing 100080 China Department of Computer Science University of Chicago Chicago IL 60637 U.S.A. ABB Corporate Research Raleigh NC 27606 U.S.A. School of Computer Science Fudan University Shanghai 201203 China School of Electronics Engineering and Computer Science Peking University Beijing 100871 China

For this special section on software systems, six research leaders in software systems, as guest editors tor this special section, discuss important issues that will shape this field＇s future research directions. The essays included in this roundtable article cover research opportunities and challenges for large-scale software systems such as querying organization- wide software behaviors （Xusheng Xiao）, logging and log analysis （jian-Ouang Lou）, engineering reliable cloud distributed systems （shan Lu）, usage data （David C. Shepherd）, clone detection and management （Xin Peng）, and code search and beyond （Qian-Xiang Wang）. - Tao Xie, Leading Editor of Software Systems.

关键词： organization-wide software behavior log analysis reliable cloud distributed system usage data clone detection and management code search