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Particle size dependence of the microsegregation and microstructure in the atomized Ni-based superalloy powders:Theoretical and experimental study

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Journal of Materials Science & Technology 2024年第4期171卷 54-65页

作者： Jikang Li Mingsheng Yang yunfei cai Yuanyuan Zhang Qingshuai Feng Jiantao Liu Tong Liu Key Laboratory of Aerospace Materials and Performance(Ministry of Education)School of Materials Science and Engineering Beihang UniversityBeijing 100191China Central Iron and Steel Research Institute Beijing 100081China

The microstructure and microsegregation of atomized powder,which depend on their sizes,are of great importance to the mechanical properties of the consolidated bulk materials.Therefore,it is necessary to reveal the relationship between particle size and powder attributes.The effects of particle size on the so-lidification characterization of the atomized Ni-based superalloy powders were studied via finite element simulation.Based on the simulations,a model was developed to predict the microsegregation and mi-crostructure of atomized powders with different sizes and study the influence of thermal history on the powder attributes during the atomization processes.The radiation heat transfer and temperature gradi-ent within the rapid solidification alloy powders were taken into account in this model.For validating the accuracy of the model,the predictions of the present model were compared with the microsegregation and microstructure of the specific size powder close to the screen mesh size.The results showed that mi-crostructure depended primarily on the temperature gradient within the powder,while the solidification rate had a more significant effect on the microsegregation.The model predicted microstructure features in agreement with the experiment,and for microsegregation,the deviations of prediction for most ele-ments were less than 10%.This work provides a new model to precisely predict the microsegregation and microstructure of the atomized alloy powders and sets a foundation to control the powder features for various engineering applications.

关键词： Particle size Solidification microstructure Microsegregation Numerical simulation

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Comparison of the Minimum Bounding Rectangle and Minimum Circumscribed Ellipse of Rain Cells from TRMM

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Advances in Atmospheric Sciences 2024年第3期41卷 391-406页

作者： Hongke cai Yaqin MAO Xuanhao ZHU yunfei FU Renjun ZHOU Plateau Atmospheric and Environment Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Center for Atmospheric Optics Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China

Based on the TRMM dataset, this paper compares the applicability of the improved MCE(minimum circumscribed ellipse), MBR(minimum bounding rectangle), and DIA(direct indexing area) methods for rain cell fitting. These three methods can reflect the geometric characteristics of clouds and apply geometric parameters to estimate the real dimensions of rain cells. The MCE method shows a major advantage in identifying the circumference of rain cells. The circumference of rain cells identified by MCE in most samples is smaller than that identified by DIA and MBR, and more similar to the observed rain cells. The area of rain cells identified by MBR is relatively robust. For rain cells composed of many pixels(N> 20), the overall performance is better than that of MCE, but the contribution of MBR to the best identification results,which have the shortest circumference and the smallest area, is less than that of MCE. The DIA method is best suited to small rain cells with a circumference of less than 100 km and an area of less than 120 km^(2), but the overall performance is mediocre. The MCE method tends to achieve the highest success at any angle, whereas there are fewer “best identification”results from DIA or MBR and more of the worst ones in the along-track direction and cross-track direction. Through this comprehensive comparison, we conclude that MCE can obtain the best fitting results with the shortest circumference and the smallest area on behalf of the high filling effect for all sizes of rain cells.

关键词： TRMM minimum bounding rectangle minimum circumscribed ellipse

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Combined Effect of Outdoor Time and Other Modifiable Factors on Myopia Incidence Among Children and Adolescents—9 PLADs,China,2020

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China CDC weekly 2024年第9期6卷 151-156,I0001,I0002页

作者： Panliang Zhong yunfei Liu Ning Ma Jiajia Dang Di Shi Shan cai Ziyue Chen Yanhui Dong Peijin Hu Jun Ma Patrick W.C Lau Randall S.Stafford Yi Song Institute of Child and Adolescent Health School of Public HealthPeking UniversityNational Health Commission Key Laboratory of Reproductive HealthBeijingChina Department of Sport Physical Education&HealthHong Kong Baptist UniversityKowloon TongHong Kong Special Administrative RegionChina Department of Medicine Stanford Prevention Research CenterStanford University School of MedicineStanfordCAUnited States

Summary What is already known about this topic?Myopia has been identified as a significant emerging challenge and policy priority among children and adolescents in China by the Ministry of Education and seven other departments.Limited research has been conducted to investigate the collective impact of outdoor time and other modifiable factors on the incidence of myopia.

关键词： Incidence collective policy

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A new approach of formation navigation derived from multi-robots cooperative online FastSLAM

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控制理论与应用（英文版） 2012年第4期10卷 451-457页

作者： yunfei cai Zhenmin TANG Chunxia ZHAO Institute of Pattern Recognition and Artificial Intelligence Nanjing University of Science and Technology

A new formation navigation approach derived from multi-robots cooperative online FastSLAM is proposed. In this approach, the leader and follower robots are defined. The posteriori estimation of the leader robot state is treated as a relative reference for all follower robots to correct their state priori estimations. The control volume of individual follower will be achieved from the results of the corrected estimation. All robots are observed as landmarks with known associations by the others and are considered in their landmarks updating. By the method, the errors of the robot posterior estimations are reduced and the formation is well kept. The simulation and physical experiment results show that the multi-robots relative localization accuracy is improved and the formation navigation control is more stable and efficient than normal leader-following strategy. The algorithm is easy in implementation.

关键词： Multi-robots Formation navigation FastSLAM

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多机械系统的固定时间一致性设计

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控制工程 2024年第1期31卷 61-69页

作者：孟云斐王保防蔡明洁青岛大学自动化学院山东青岛266071 青岛大学山东省工业控制技术重点实验室山东青岛266071

针对具有未知非线性特性和扰动的多机械系统一致性问题,提出了一种基于径向基函数(radial basis function,RBF)神经网络的固定时间一致性算法。首先,建立了存在未知非线性函数项和不确定扰动的多机械系统模型;其次,根据系统模型设计了... 详细信息

针对具有未知非线性特性和扰动的多机械系统一致性问题,提出了一种基于径向基函数(radial basis function,RBF)神经网络的固定时间一致性算法。首先,建立了存在未知非线性函数项和不确定扰动的多机械系统模型;其次,根据系统模型设计了一种固定时间一致性协议,利用RBF神经网络来逼近模型中未知的非线性项;再次,利用李雅普诺夫稳定性理论证明了任意一对机械系统的位置和速度误差可以在固定时间内收敛到零的小邻域内;最后,通过MATLAB仿真软件验证所设计协议的有效性。仿真结果表明,所提出的协议能够实现预期目标。

关键词：固定时间一致性多机械系统神经网络李雅普诺夫理论

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Theory and Application of Multi-robot Service-oriented Architecture

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IEEE/CAA Journal of Automatica Sinica 2016年第1期3卷 15-25页

作者： yunfei cai Zhenmin Tang Yuhua Ding Bin Qian Institute of Intelligent Robots Nanjing University of Science and Technology

In order to solve the problem of heterogeneity in multi-robot cooperation, a new service-oriented architecture is proposed for multi-robot cooperation. Service provision and energy consumption are the basic cooperative behaviors. A set of basic concepts of robot service are proposed. A layered multi-robot service-oriented architecture is designed. Finally, the experiments illustrate the superiority of the proposed architecture which makes robot's underlying functional components be transparently encapsulated and the services in upper layer be transparently invoked, which will effectively avoid the impact of heterogeneous characteristics in multi-robot cooperation and facilitate the system construction, expansion, restructuring and maintenance.

关键词： Multi-robot cooperation architecture serviceoriented

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高山广播电视无线发射台电力系统改造案例分析

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电视技术 2024年第6期48卷 143-147页

作者：蔡允飞文山电视调频骨干转播台云南文山663000

安全播出是广播电视工作的生命线,电力保障系统是保障安全播出的基础。以文山电视调频骨干转播台电力系统优化改造为例,介绍如何结合高山台站实际情况进行电力系统改造,供业内人士参考。

关键词：广播电视电力安全配电系统防雷接地系统

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多层核壳结构Fe@Al-Ti载氧体化学链制氢性能研究

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燃料化学学报（中英文） 2024年第3期52卷 353-361页

作者：蔡志阳张俊贤汪欣肖慧霞高云飞王亦飞华东理工大学资源与环境工程学院上海市煤气化工程技术研究中心上海200237

Fe-Al-Ti载氧体在化学链制氢工艺中具有良好的循环稳定性和抗积炭性能,但反应形成FeAl_(2)O_(4)会降低抗烧结性能和氢气产率。为抑制FeAl_(2)O_(4)的生成并进一步提升载氧体反应性能,本研究采用自组装模板燃烧法制备多层核壳结构载氧体,... 详细信息

Fe-Al-Ti载氧体在化学链制氢工艺中具有良好的循环稳定性和抗积炭性能,但反应形成FeAl_(2)O_(4)会降低抗烧结性能和氢气产率。为抑制FeAl_(2)O_(4)的生成并进一步提升载氧体反应性能,本研究采用自组装模板燃烧法制备多层核壳结构载氧体,以TiO_(2)为介层阻隔Fe2O3与Al2O3,形成多层核壳Fe@Al-Ti载氧体,在固定床上进行化学链制氢循环,评价多层核壳结构对反应性能的影响。结果表明,Fe@Al-Ti载氧体的介层有效阻隔Fe_(2)O_(3)与Al_(2)O_(3)的接触,抑制了FeAl_(2)O_(4)形成,抗烧结性能得到进一步提升。Fe@Al-Ti载氧体在化学链制氢循环实验中无明显积炭和团聚现象,制氢能力随循环次数逐渐增加,循环稳定性较好;尤其物质的量比Al∶Ti=3.5∶1的核壳载氧体的碳转化率、制氢率和储氧量最高,分别为57.4%、75.0%和6.01 mmol/g,比非核壳Fe-Al-Ti载氧体分别增加28.4%、30.0%、26.9%。

关键词：化学链制氢 Fe_(2)O_(3)/TiO_(2)/Al_(2)O_(3) 核壳结构固定床

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Ultralong Stretchable Soft Actuator(US2A):Design,Modeling and Application

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 280-291页

作者： Wenbiao Wang yunfei Zhu Shibo cai Guanjun Bao Key Laboratory of Special Purpose Equipment and Advanced Processing Technology Ministry of EducationZhejiang University of TechnologyHangzhou310014China Beijing Institute of Spacecraft Environment Engineering China Academy of Space TechnologyBeijing100094China

Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a bellows woven sleeve.The maximal extension can be conveniently regulated by just adjusting the wrinkles’initial angle of the bellows woven sleeve.The kinematics of US2A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated.Based on the principle of virtual work,the actuating models have been established:the pressure-elongation model and the pressure-force model.These models reflect the influence of the silicone tube’s shell thickness and material properties on the pneumatic muscle’s performance,which facilitates the optimal design of US2A for various working conditions.The experimental results showed that the maximum elongation of the US2A prototype is 257%,and the effective elongation could be variably regulated in the range of 0 and 257%.The proposed models were also verified by pressure-elongation and pressure-force experiments,with an average error of 5%and 2.5%,respectively.Finally,based on the US2A,we designed a pneumatic rehabilitation glove,soft arm robot,and rigid-soft coupling continuous robot,which further verified the feasibility of US2A as a soft driving component.

关键词： Soft robotics Soft actuator Pneumatic artificial muscle Modeling

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城乡建设领域北斗系统应用现状与趋势

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城市发展研究 2024年第5期31卷 26-29页

作者：于静郭鹏张华薛云飞蔡文婷钟泽鹏住房和城乡建设部信息中心

通过梳理城乡建设领域北斗系统的主要应用场景、应用特点和技术路径，分析了北斗的行业应用潜力，基于北斗系统在城乡建设领域的应用现状，评估了发展趋势。北斗系统通过与物联传感、通信、遥感、地理信息等技术融合，重点赋能房屋建筑... 详细信息

通过梳理城乡建设领域北斗系统的主要应用场景、应用特点和技术路径，分析了北斗的行业应用潜力，基于北斗系统在城乡建设领域的应用现状，评估了发展趋势。北斗系统通过与物联传感、通信、遥感、地理信息等技术融合，重点赋能房屋建筑安全监测、市政基础设施运行管理、城市运行管理服务、工程测量与管理等行业应用，支撑好房子、好小区、好社区、好城区“四好”建设。未来，北斗系统将会进一步在新型城市基础设施建设、提升城市运行安全管理能力、助力工程测量与管理进一步数字化转型等方面发挥作用，城乡建设领域的北斗应用标准也将持续完善，不断提升北斗系统在城乡建设领域的应用规模和应用质量。

关键词：北斗系统城乡建设领域

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