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Effect of thermal-cycling on the piezoelectricity of 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 Pb-free piezoceramic

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Journal of Alloys and Compounds 2020年 847卷

作者： Yanshuang Hao Chang Liu Liqiang He Yuanchao Ji Luo Zhao Jinghui Gao Shuai Ren Mengyao Guo Zhufeng Hou Bo Da Xiaobing Ren Frontier Institute of Science and Technology And State Key Laboratory for Mechanical Behaviour of Materials And MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Xi’an Jiaotong University Xi’an 710049 China Center for Functional Materials National Institute for Materials Science Tsukuba 305-0047 Ibaraki Japan State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University Xi’an 710049 China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou 350002 China Research and Services Division of Materials Data and Integrated System National Institute for Materials Science Tsukuba 305-0044 Ibaraki Japan

The reliability of piezoelectricity under thermal-cycling is an important consideration for the practical application of Pb-free piezoelectric materials. In this paper, we investigated the effect of thermal-cycling on the piezoelectricity of 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) Pb-free piezoceramic. The results show that, in BZT-BCT, the tetragonal-orthorhombic (T-O) transition causes a strong piezoelectricity degradation (∼40% reduction after 60 thermal cycles between −40 °C and 50 °C), whereas the orthorhombic-rhombohedral (O-R) transition only leads to negligible degradation during the thermal-cycling test, indicating a weak depoling effect. The comparative studies made between BZT-BCT and BaTiO 3 (BT) reveal that the weak depoling effect results from the diffuseness of the O-R transition in BZT-BCT and weak domain pattern change across the transition. Our work implies that Pb-free piezoelectrics with good thermal-cycling stability can be achieved through engineering the normal ferroelectric-to-ferroelectric transition to a diffused one, which may help to design new Pb-free piezoelectric materials with good thermal-cycling stability.

关键词： Thermal cycling Phase transition Pb-free Diffuse phase transition

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A design of hardware-in-the-loop real-time simulation for large-scale complex electromechanical system

A design of hardware-in-the-loop real-time simulation for la...

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CSAA/IET International Conference on Aircraft Utility systems (AUS 2018)

作者： Zhentian Liu Guangsen Wang Chengmei Lin Zhiwei Wang Jing Li National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval Univ. of Engineering Wuhan China Wuhan Marine Machinery Co. Ltd Wuhan China

ISBN: (纸本)9781510872745

The more electric aircraft (MEA), belonging to the large-scale complex electromechanical system (LSCES), always has a large-scale complex structure, of which the design, testing, and evaluation may be a challenging task. In order to analyze the impact of various factors on the system performance and reduce the potential risk, it is advantageous to establish a hardware-in-the-loop (HIL) real-time simulation platform for MEA. From this purpose, some key processes are suggested to clear the way for an efficient and accurate design. First, the principles of system partitioning and high-performance communication network are presented for distributed parallel computation. Then, algorithms are discussed and compared aiming to compensate inter-simulation time-step switching error caused by high-frequency switches which are widely used in MEA. Finally, an automation test method based on Monte Carlo (MC) and Genetic Algorithm (GA) methodology is proposed. In the experimental part, a permanent magnet synchronous motor (PMSM) in HIL mode is presented to demonstrate the practicality, with the results of the offline and real-time simulation compared. In short, this paper provides a guidance for establishing an HIL platform for LSCES.

关键词： MEA Large-scale complex electromechanical system Real-time simulation Monte cario Genetic algorithm

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Theoretical prediction and experimental testing of mechanical properties for 3d printed silk fibroin-type II collagen scaffolds for cartilage regeneration

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MCB Molecular and Cellular Biomechanics 2018年第2期15卷 85-98页

作者： Gao, Lilan Yuan, Qingxian Li, Ruixin Chen, Lei Zhang, Chunqiu Zhang, Xizheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin30000 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300000 China Hospital of Stomatolgy NanKai University Tianjin300000 China

Silk fibroin-type II collagen scaffold was made by 3D printing technique and freeze-drying method, and its mechanical properties were studied by experiments and theoretical prediction. The results show that the three-dimensional silk fibroin-typeII collagen scaffold has good porosity and water absorption, which is (89.3%+3.26%) and (824.09%+93.05%), respectively. With the given strain value, the stress of scaffold decreases rapidly firstly and then tends to be stable during the stress relaxation. Both initial and instantaneous stresses increase with increase of applied strain value. The creep strains of scaffold with different stress levels show the two stages: the rapidly increasing stage and the second stable stage. It is noted that the scaffold with compressive stress of less than 35 kPa can recover when the compressive stress is removed. However when the compressive stress is higher than 50 kPa, the scaffold is damaged and its structure is destroyed. Not only the compressive property but tensile property of scaffold are dependent on the applied displacement rate or strain rate. Its compressive elastic modulus and tensile modulus increase with increase of strain rate or displacement rate. The nonlinear relaxation model and creep model were constructed respectively and applied to predict the stress relaxation behavior and creep behavior of scaffold. It is found that there are good agreements between the experimental data and predictions, which mean that the built theoretical model can predict the mechanical behavior of scaffold. Copyright © 2018 Tech science Press.

关键词： Strain rate

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Smart radio environments

arXiv

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arXiv 2021年

作者： Gradoni, Gabriele Renzo, Marco Di Díaz-Rubio, Ana Tretyakov, Sergei A. Caloz, Christophe Gradoni, Gabriele Peng, Zhen Alu, Andrea Lerosey, Geoffroy Fink, Mathias Galdi, Vincenzo Cui, Tie Jun Frazier, Benjamin W. Anlage, Steven M. Salucci, Marco Massa, Andrea Cheng, Qiang Wang, Jinghe Jin, Shi Dardari, Davide Decarli, Nicoló Yurduseven, Okan Matthaiou, Michail Kenney, Mitchell Gordon, George Georgiou, Orestis Nguyen, Cam Ly Martini, Enrica Maci, Stefano Wakatsuchi, Hiroki Phang, Sendy School of Mathematical Sciences Department of Electrical and Electronic Engineering University of Nottingham Nottingham United Kingdom Laboratoire des Signaux et Systémes CNRS CentraleSupélec Université Paris-Saclay Gif-sur-Yvette Paris France Department of of Electronics and Nanoengineering Aalto University Espoo Finland META Research Group KU Leuven Belgium School of Mathematical Sciences Department of Electrical and Electronic Engineering University of Nottingham University Park NG72RD United Kingdom Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign IL United States Advanced Science Research Center City University of New York United States Greenerwave 6 rue Jean Calvin Paris75005 France Institut Langevin 1 rue Jussieu Paris75005 France Fields & Waves Lab Department of Engineering University of Sannio Benevento Italy State Key Laboratory of Millimeter Waves Southeast University Nanjing China Applied Physics Laboratory Johns Hopkins University LaurelMD20723 United States Department of Electrical and Computer Engineering Department of Physics Quantum Materials Center University of Maryland College ParkMD20742 United States Trento Italy Chengdu China Beijing China Institute of Electromagnetic Space State Key Laboratory of Millimeter Waves Southeast University Nanjing210096 China National Mobile Communications Research Laboratory Southeast University Nanjing China University of Bologna Bologna Italy Bologna Italy Centre for Wireless Innovation Institute of Electronics Communications and Information Technology Queen’s University Belfast Belfast United Kingdom Department of Electrical and Electronic Engineering University of Nottingham Nottingham United Kingdom Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus Wireless System Laboratory Corporate Research & Development Center Toshiba Corporation Kawasaki Japan Department of Information Engineering an

This Roadmap takes the reader on a journey through the research in electromagnetic wave propagation control via reconfigurable intelligent surfaces. Meta-surface modelling and design methods are reviewed along with physical realisation techniques. Several wireless applications are discussed, including beam-forming, focusing, imaging, localisation, and sensing, some rooted in novel architectures for future mobile communications networks towards 6G. © 2021, CC BY.

关键词： Electromagnetic wave propagation

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Near-Optimal Online Motion Planning of Connected and Automated Vehicles at a Signal-Free and Lane-Free Intersection

Near-Optimal Online Motion Planning of Connected and Automat...

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2018 IEEE Intelligent Vehicles Symposium, IV 2018

作者： Li, Bai Zhang, Youmin Zhang, Yue Jia, Ning Ge, Yuming Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xi'An University of Technology Xi'an710048 China College of Control Science and Engineering Zhejiang University Hangzhou310027 China Department of Mechanical Industrial and Aerospace Engineering Concordia Institute of Aerospace Design and Innovation Concordia University Montreal Canada Division of Systems Engineering Center for Information and Systems Engineering Boston University BostonMA02215 United States Institute of Systems Engineering Tianjin University Tianjin300072 China China Academy of Information and Communications Technology Beijing100191 China

ISBN: (纸本)9781538644522

In this paper, we propose a cooperative motion planning method for a group of connected and automated vehicles (CAVs) crossing a lane-free intersection without using explicit traffic signaling. This multi-vehicle motion planning task is formulated as a centralized optimal control problem. However, the solution to this optimal control problem is numerically intractable due to the high dimensionality of the collision-avoidance constraints and the nonlinearity of the vehicle kinematics. A two-stage strategy is proposed for generating online solutions: at Stage 1, the CAVs are requested to reach a standard formation before entering the intersection;at Stage 2, the vehicles cross the intersection. As the motion planning sub-problem at Stage 2 begins with a standard configuration, the optimal solution to this standard sub-problem can be computed offline in advance and applied online directly. On the other hand, the formation reconfiguration sub-problem at Stage 1 is easy to solve online. Through dividing the entire dynamic process into two periods, the difficulties in the original optimal control problem are significantly reduced so that the real-time performance is achieved. © 2018 IEEE.

关键词： Motion planning

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The parareal method for solving space-dependent neutron kinetics equations in hexagonal-z geometry

The parareal method for solving space-dependent neutron kine...

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2017 Transactions of the American Nuclear Society, ANS 2017

作者： Cai, Yun Hou, Jingjing Peng, Xingjie Li, Qing Wang, Kan Department of Engineering Physics Tsinghua University Beijing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China China Core and Fuel Management Department CNNP Nuclear Power Operation Management Co. Ltd China

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Diametrical effects of supercritical water heat transfer in annular channels 17

Diametrical effects of supercritical water heat transfer in ...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Dongliang, Ma Tao, Zhou Bing, Li Yanping, Huang Zejun, Xiao School of Nuclear science and Engineering North China Electric Power University Beijing102026 China Institute of Nuclear Thermal-hydraulic Safety and Standardization North China Electric Power University Beijing102206 China Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy North China Electric Power University Beijing102206 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China HualongPressuried Water Reactor Technology Corporation Ltd. Beijing100037 China

Supercritical water cooled reactor (SCWR) is one of the six types of Generation IV reactor in the international use. For supercritical water cooled reactor, the supercritical water has many peculiar properties near the critical point. During the loss of flow accident, there is a practical significance of carrying out research on the coolant heat load capacity and stability of the flow in the natural circulation loop, which helps to reduce the probability of core meltdown and improve the safety of the reactor. Compared with natural circulation, forced circulation also holds an important position due to its large flow rate in different sizes of the annular channel (resulting in different heat transfer rates). The forced circulation in supercritical water channels is largely based on the experimental data, and the use of CFX software in ANSYS platform provides a model for numerical simulation analysis. Heat transfer was calculated at different annular channel sizes for the supercritical water. Results of the calculation show that a small size of annular pipe channel helps to enhance the heat transfer rates at low pressures. Heat transfer is further strengthened for low heating power and narrow annular channel sizes. The enhancement in heat transfer rate is much more apparent (in small pipes) for larger flow rates. However, there is a corresponding increase in the local eddy viscosity values in annular channels of smaller sizes. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Computer software

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Research on load spectrum of CNC machine tool based on cutting current signal 23

Research on load spectrum of CNC machine tool based on cutti...

引用

23rd ISSAT International Conference on Reliability and Quality in design 2017

作者： Wu, Ying Li, Bin Li, Jindong Ding, Subao National NC System Engineering Research Centre Huazhong University of Science and Technology Wuhan China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan China Co. Ltd Shenyang China

ISBN: (纸本)9780991057641

Load spectrum is the basis of reliability analysis of CNC machine tools. Utilizing the characteristics of current signal collection, which are easy to collect large data for a long time with no effect on the production process, the method of cutting force estimation based on current signal is studied in this paper. A modelling method of the load spectrum of machine tool based on actual cutting current signal is proposed. The life cycle data acquisition of the feed system's current signal on horizontal machining center is carried out during the actual production process, and the load spectrum of horizontal machining center is established by using the current signal data.

关键词： Machining centers

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Fracture mechanics analysis of cracked structures using weight function and neural network method

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IOP Conference Series: Materials science and Engineering 2018年第1期372卷

作者： J G Chen F G Zang Y Yang K K Shi X L Fu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China China

Stress intensity factors(SIFs) due to thermal-mechanical load has been established by using weight function method. Two reference stress states sere used to determine the coefficients in the weight function. Results were evaluated by using data from literature and show a good agreement between them. So, the SIFs can be determined quickly using the weight function obtained when cracks subjected to arbitrary loads, and presented method can be used for probabilistic fracture mechanics analysis. A probabilistic methodology considering Monte-Carlo with neural network (MCNN) has been developed. The results indicate that an accurate probabilistic characteristic of the KI can be obtained by using the developed method. The probability of failure increases with the increasing of loads, and the relationship between is nonlinear.

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A core design of breeding BWR

A core design of breeding BWR

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2017 Transactions of the American Nuclear Society, ANS 2017

作者： Guo, Rui Yamaji, Akifumi Qin, Xue Ji, Wenhao Jiang, Zhumin Wang, Shuai Cai, Yun Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Huayang Chengdu610041 China Cooperative Major in Nuclear Energy Graduate School of Advanced Science and Engineering Waseda University 3-4-1 Okubo Tokyo169-8555 Japan

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