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arXiv 2023年

作者： Wang, Chao Jian, Nan Yin, Meijie Zhang, Xi Yang, Zhi Mo, Xiuhao Kikkawa, Takashi Daimon, Shunsuke Saitoh, Eiji Li, Qian Yan, Wensheng Hou, Dazhi Yang, Lei Diao, Dongfeng Institute of Nanosurface Science and Engineering Shenzhen University Shenzhen518060 China Electron Microscopy Center of Shenzhen University Shenzhen518060 China National Key Laboratory of Radio Frequency Heterogeneous Integration Shenzhen University Shenzhen518060 China Department of Applied Physics The University of Tokyo Tokyo113-8656 Japan Tokyo152-8550 Japan Institute for AI and Beyond The University of Tokyo Tokyo113-8656 Japan WPI Advanced Institute for Materials Research Tohoku University Sendai980-8577 Japan National Synchrotron Radiation Laboratory School of Nuclear Science and Technology University of Science and Technology of China Anhui Hefei230029 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei230026 China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong University Xi’an710049 China

The emergence of bulk carbon ferromagnetism is long-expected over years. At nanoscale, carbon ferromagnetism was detected in graphene nanoribbon segments1–3, graphene triangulene dimers4,5, and other graphene-like molecules6–8 by analyzing their magnetic edge states via scanning tunneling microscopy(STM)9, and its origin can be explained by local redistribution of electron wave function3,5,8. Recently, there are experimental efforts on discovering orbital ferromagnetism in twisted bilayer graphene10,11, which is still limited in STM region. In larger scale, carbon ferromagnetism can be created by deliberately producing defects in graphite12–14, and detected by macroscopic technical magnetization. Meanwhile, it becomes crucial to determine that the detected magnetization is originated from carbon rather than from magnetic impurities. One solution to eliminate this uncertainty is X-ray magnetic circular dichroism (XMCD). A contrast of dichroism at π* absorption energy was observed in the scanning x-ray microscope image of proton-irradiated graphite15. Nonetheless, a reproducible, full section of XMCD spectrum across C-1s absorption energy has not appeared yet, which should be decisive for assuring the indisputable existence of bulk carbon ferromagnetism. Besides, the lack of direct observation on the atomic structure of the ferromagnetic carbon leaves the structural origin of its ferromagnetism still in mist. In this work, for detecting bulk carbon ferromagnetism, we managed to grow all-carbon film consisting of vertically aligned graphene multi-edge (VGME), which wove into a three-dimensional hyperfine-porous network. Magnetization (M-H) curves and XMCD spectra co-confirmed bulk carbon ferromagnetism of VGME at room temperature, with the average unit magnetic momentum of ~0.0006 μB/atom. The influence of magnetic impurities on magnetization was excluded by both absorption spectra and inductively coupled plasma mass spectrometry measurements. The spin transfer behavio

关键词： Ferromagnetism

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Coupled fluid-thermal investigation on non-ablative thermal protection system with spiked body and opposing jet combined configuration

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Chinese Journal of Aeronautics 2019年第6期32卷 1390-1402页

作者： Jie HUANG Weixing YAO Xianyang SHAN State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and AstronauticsNanjing 210016China System Design Institute Hubei Aerospace Technology AcademyWuhan 430040China

In this paper, a Non-Ablative Thermal Protection system(NATPS) with the spiked body and the opposing jet combined configuration is proposed to reduce the aerodynamic heating of the hypersonic vehicle, and the coupled fluid-thermal numerical analysis is performed to study the thermal control performance of the NATPS. The results show that the spiked body pushes the bow shock away from the protected structure and thus reduces the shock intensity and the wall heat flux. In addition, the low temperature gas of the opposing jet separates the high temperature gas behind the shock from the nose cone of the spiked body, ensuring the non-ablative property of the spiked body. Therefore, the NATPS reduces the aerodynamic heating by the reconfiguration of the flow field, and the thermal control efficiency of the system is better than the Thermal Protection system(TPS) with the single spiked body and the single opposing jet. The influencing factors of the NATPS are analyzed. Both increasing the length of the spiked body and reducing the total temperature of the opposing jet can improve the thermal control performance of the NATPS and the nonablative property of the spiked body. However, increasing the heat conductivity coefficient of the spiked body can enhance benefit the non-ablative property of the spiked body, but has little influence on the thermal control performance of the NATPS.

关键词： Coupled method Non-ablative Opposing jet Spiked body Thermal protection system

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Information Freshness in A Dual Monitoring system

Information Freshness in A Dual Monitoring System

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GLOBECOM 2022 - 2022 IEEE Global Communications Conference

作者： Dapeng Deng Zhengchuan Chen Howard H. Yang Nikolaos Pappas Limei Hu Min Wang Yunjian Jia Tony Q.S. Quek School of Microelectronics and Communication Engineering Chongqing University Chongqing China National Mobile Communications Research Laboratory Southeast University Nanjing China Zhejiang University/University of Illinois at Urbana-Champaign Institute Zhejiang University Haining China Department of Computer and Information Science Linkoping University Linkoping Sweden School of Optoelectronics Engineering Chongqing University of Posts and Telecommunications Chongqing China Information System Technology and Design Pillar Singapore University of Technology and Design Singapore

ISBN: (纸本)9781665435413

We study the average age of information (AoI) and peak AoI (PAoI) of a dual-queue status update system that monitors a common stochastic process. We capture the state transition characteristics of the considered system by establishing a Markov chain. Using the state flow graph analysis method, we derive closed-form expressions of the average peak age of information (PAoI) and the average age of information (AoI) for the dual-queue update system. The numerical results show that compared with the single-queue update system, the average PAoI of the dual-queue update system is reduced by 33.5% and the average AoI dropped by 37.5%.

关键词： Closed-form solutions Markov processes Reliability theory Information age Sensor systems Real-time systems Sensors

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The Impact Failure and Energy Dissipation Mechanism of Polyethylene Laminates

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Journal of Wuhan University of technology(Materials science) 2019年第3期34卷 723-727页

作者： SHU Zaiqin ZHANG Jinyong State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Institute of Material Science and EngineeringWuhan University of TechnologyWuhan430070China System Design Institute of Hubei Aerospace Technology Academy Wuhan430040China

The damage mechanism and energy dissipation of the Polyethylene (PE) laminates in impacting was investigated. It was found that the dissipated energy of the impacting sphere bullet by the 1-mmthick PE plate firstly increased with the impacting velocity increasing from 50 to about 300 m/s, and then decreased with the impacting velocity increasing up to 600 m/s. According to the measured deformation and damage degree, a numerical simulation of the dissipated energy was made and obvious offset was found with the experimental results. The quasi-static properties of the PE fibers, decreasing with increase in tensile velocity, may be the main reason for the offset.

关键词： polyethylene ballistic impact energy dissipation strain rate

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Numerical analyses and experimental verification on multiphase flow measurements using a gamma-ray densitometer with blind-tee mixing 27

Numerical analyses and experimental verification on multipha...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Ma, Yugao Cui, Yinghuan Hao, Yisheng Huang, Shanfang Pan, Yanzhi Yu, Hongxing Department of Engineering Physics Tsinghua University Beijing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9784888983051

Gas-liquid two-phase flow widely exists in nuclear industry, where the heat flux is quite high. Accurate predictions of key parameters such as void fraction and gas volume fraction are important to the insurance of reactor safety operation. However, the accuracy of most multiphase flowmeters is flow-pattern dependent. A common way to homogenize the gas-liquid mixture and to eliminate the flow pattern effects is to install a blind-tee upstream of the flow measurement section to transform the horizontal flow to vertical upward flow. It is therefore of great interest to verify the effectiveness of flow mixing caused by blind-tee via experiments or simulation. In this study, the three-dimensional transient numerical simulation on gas-liquid two-phase flow was carried out by a commercial CFD software Fluent, using VOF model as multiphase model and Realizable k-Ε model as turbulence model. The results show that the flow develops from centrifugal flow to homogenous flow after passing around the bend and recovers its intermittent nature further downstream. CFD simulation analysis shows that there is a relatively ideal mixing effect after about 7 pipe diameters downstream. Therefore, the complexity of horizontal flow and intermittent flow are avoided by means of device design and measurement position optimization, which simplifies the measurement and calculation model. A flow-pattern based flow rate model is established by introducing the homogeneous-degree evaluation factor. The formula is simple and yet accurate. The relative average error of the model for predicting the total mass flow rate is within 2.66%. Copyright © 2018-2019 by JSME

关键词： Flowmeters

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Research on Optimization of Key Parts of Nuclear reactor Based on Finite Element Simulation

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IOP Conference Series: Earth and Environmental science 2021年第3期632卷

作者： Bo Yang Tianda Yu Qiang Deng Cong Chen Fengshou Zhang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institution of China Sichuan ChengDu 610041 China

In view of the higher technical requirements of the third generation PWR for the control rod drive mechanism (CRDM), China's third generation nuclear reactor CRDM hook parts are designed to multi-tooth hook with wear-resistant surfacing. The surfacing welding process is simulated and optimized based on finite element simulation, and reasonable welding process and parameters are determined by simulation results in this *** to the optimized welding process, the parts are trial-produced, and the parts of the hook are subjected to metallographic inspection, hardness test and thermal life test. The results show that the optimized hook parts have high hardness and wear resistance, and meet the requirements of the third generation PWR nuclear power plant.

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A transfer learning based geometric position-driven machining error prediction method for different working conditions*

A transfer learning based geometric position-driven machinin...

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International Conference on Mechatronics and Machine Vision in Practice (M2VIP)

作者： Teng Zhang Hao Sun Lin Zhou Shengqiang Zhao Fangyu Peng Rong Yan National NC System Engineering Research Center School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China Wuhan Digital Design and Manufacturing Innovation Center Co. Ltd China Wuhan China State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665431545

Machining error is one of the most important indicators to evaluate the processing quality of thin-walled parts. With the development of Data science, the data-driven methods have become popular. But the condition that the model can work accurately on a new task is that the feature space and distribution of the data are the same. A sample-based transfer learning method driven by geometric position is utilized to quickly predict the machining errors of thin-walled parts under different working conditions. This method can fully learn the knowledge related to machining errors contained in the data through model training, and can apply this knowledge to accurately and quickly forecast machining errors under new working conditions. In the experimental scenario, this method has outstanding predictive performance. The average determination coefficient of the four groups of target domain experiments reached 0.96, and the average root mean square error is less than the machining error acquisition time to 22% of the original, reducing the dependence on time-consuming and expensive measurements greatly.

关键词： Employee welfare Training Mechatronics Transfer learning Machining Predictive models Data models

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Tool wear parameters identification in precision milling using a hybrid model combining cutting forces analytical model and Gaussian process regression method*

Tool wear parameters identification in precision milling usi...

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International Conference on Mechatronics and Machine Vision in Practice (M2VIP)

作者： Shengqiang Zhao Lin Zhou Hao Sun Fangyu Peng Rong Yan Teng Zhang National NC System Engineering Research Center School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China Wuhan Digital Design and Manufacturing Innovation Center Co. Ltd China Wuhan China State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665431545

In precision milling, tool wear has a significant impact on tool life prediction, machining accuracy and surface quality evaluation of workpiece. Tool wear pattern generally includes the increase of the tool flank wear width, as well as the expansion of the edge radius in precision process. Therefore, two tool wear parameters in precision milling have been generalized in this paper. The milling cutting force analytical model considering tool wear is set up to generate the data related to cutting force and tool wear parameters, which can be used as the dataset to construct and train the Gaussian process regression model. Finally, the trained regression model can output the prediction of tool flank wear width and edge radius as measured cutting forces treated as input values, which is helpful to realize the online monitoring of tool wear in the processing site environment. Consequently, the average relative prediction errors of tool flank wear width and edge radius are controlled within 2%, with the prediction time within 100ms.

关键词： Training Analytical models Parameter estimation Machine learning algorithms Force Milling Gaussian processes

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A hybrid mechanism-based and data-driven approach for the calibration of physical properties of Ni-based superalloy GH3128*

A hybrid mechanism-based and data-driven approach for the ca...

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International Conference on Mechatronics and Machine Vision in Practice (M2VIP)

作者： Hao Sun Lin Zhou Shengqiang Zhao Teng Zhang Fangyu Peng Rong Yan National NC System Engineering Research Center School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China Wuhan Digital Design and Manufacturing Innovation Center Co. Ltd China Wuhan China State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781665431545

Within the finite element simulation model of metal manufacturing processes, the setting of physical properties of the materials will significantly affect the final simulation results. In this paper, a hybrid approach to integrate mechanical models and experimental data is proposed to identify the constitutive parameters and tool-chip friction coefficient of superalloy GH3128. Firstly, mechanical model is established and the relation between the constitutive parameters and the measured shear flow stress is determined. Combined with Bayesian inference, the fast inverse identification of the above parameters is realized. Then, a finite element surrogate model and Bayesian framework are fused for calibrating tool-chip friction coefficient. Finally, the effectiveness of the proposed approach is verified through milling experiments. The prediction accuracy of the prediction model are significantly improved by considering the uncertainties of physical properties. The relative error of the model in direction and direction are 11.4681% and 4.2989%, respectively.

关键词： Uncertainty Friction Simulation Metals Milling Predictive models Finite element analysis

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Time-varying Characteristics of mmWave Channel based on the Clustered Sparsity Model

Time-varying Characteristics of mmWave Channel based on the ...

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IEEE Conference on Vehicular technology (VTC)

作者： Lijun Yang Haitao Lu Xinchao Ge Zhixin Sun Pan Cao School of Internet of Things Nanjing University of Posts and Telecommunications Nanjing China RAN System Design Dept. ZTE Corporation Shenzhen China Shenzhen Key Laboratory of 5G RAN Security Technology Research and Application Shenzhen China School of Modern Posts Nanjing University of Posts and Telecommunications Nanjing China School of Physics Engineering and Computer Science University of Hertfordshire Hatfield UK

A better understanding of the mmWave channel coherence time will play a significant role in both communication and sensing. Traditional literatures consider that the channel coherence time in mmWave communication will be very short due to high frequency, which makes the channel estimation more difficult. However, we believe that the propagation characteristics of the mmWave channel will affect its coherence time, i.e., channel sparsity may limit its time variability. In this paper, we investigate the time-varying nature of mmWave channel by analyzing its Doppler spread based on the clustered sparsity model. After the derivation of Doppler spectrum DPS and the simulation analysis based on the two-cluster channel, we found that the maximum angle between clusters and the power distribution between clusters are two main factors limiting the Doppler spread. Finally, the realistic mmWave NYUSIM model is used for Doppler spread comparative analysis with Clarke’s model and find that Doppler spread of NYUSIM channel is far less than that estimated based on Clarke’s model. Thus, it is demonstrated that even if the mmWave frequency is high, the clustered sparsity characteristics makes its channel coherence time not as short as thought intuitively, which is meaningful for mmWave vehicular sensing and communication.

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